I will try it, thanks.
It is plugged directly into my MacBook's USB port.
About the performance meter, notice that the first time I hit play, the meters do not show overload, and the second time I play, it starts to jitter and show overload. And it doesn't happen when using other interfaces.
Thanks for the quick response!
Edit:
Unfortunately, it still happens in v3.33

The problem persists. Even if I turn off all plugins and sends, it still jitters.
When it finally stops jittering, it displays a weird message about the sample rate, although it is set to 44.1k in the driver and in logic.
You can see this message at the end of this video, where I play with all plugins off.
https://youtu.be/CvWwcGLNx8k

Sorry, I am not familiar with the vocabulary
I have tried to switch this setting on and off, but I still get hick-ups.
I also reinstalled 4.14 and made sure that there are no remains of 3.33 by following this post: https://forum.rme-audio.de/viewtopic.ph … 04#p211004
And still, the problem persists.
I don't know what else to do

Hello, I'd never used Mac ....

Yes, the message at the end shouldn't appear, seems there is any wrong set in Fireface USB Settings or Logic config. Have you seen it @waedi?

The error message at the end of the video says it clearly: audio / midi sync problems!
So my questions are: what midi hardware is involved? What else in the project is midi relevant? What are your midi settings for the UCX II? Are there some midi commands in the Logic project? Midi clock in use?
The other thing I can see in the video is the weird mic symbol in macOS menu bar top right. It comes and goes randomly, sometimes with graphic error (the latter seems to be a small bug in macOS, I also have this sometimes but didn’t matter so far).
EDIT: And yes, as waedi states often plugins are causing strange errors. Even when they are deactivated, they are still part of the project.

Especially for older AU plugins (Intel Only) - Logic has to be run in Rosetta Mode once, to be able to validate them.
Then Logic/Mac translates them via AUHostingCompatibilityService (?Rosetta) in Background, thus Logic is switched back to native ARM Mode.

"Replace it with onboard or request an update" is not always possible or suitable (old Projects, or if the manufacturer does not exist anymore, or no updates)...

I had a similar situation, too.
You can easily check this, if you open the ActivityMonitor app and look for "AUHostingCompatibilityService". If you see high CPU Load for this process during the overloads - thats the reason!
To get behind, which particular plugin causes the overload: It is not enough to disable it via Mixer. You have to enable the Track Header Component for On/Off first (then you will see the blue button on each track). Then disable every track one by one to see if it gets better...

Another reason could be as misconfiguration in the projects sync setting (espacially incorrect MTC Settings).

And another reason could also be: too low I/O buffers for such large projects in Logic Audio Settings.

Thank you all for the responses and the will to help, I really appreciate that!
I will answer all the questions you asked:

Yes, and it does not produce the problem. As I said in the beginning, it happens in busier sessions with multiple audio channels and plugins, although it can happen with all plugins and sends off as well.
Please note that the problem does not occur when I change the output device to the mac's speakers, or a different audio interface like focusrite scarlett. This is why I'm writing here in the forum. I can film that for you if it helps.

I meant when logic runs with rosetta, and the output device is UCX II, the problem does not produce.
Like you I thought it might be a plugin that causes that but turning off all plugins does not eliminate the problem, and as I said before, when using other output devices it works fine.

That's right, it shows weird sample rates in this message after the stuttering ends. Both the USB settings and logic pro are set to 44.1k.

In the second video, I show no overload; the performance meters are reaching halfway.
In this project that I filmed there are only 28 audio channels. That should be nothing for my Macbook pro. I mixed sessions with way more tracks then that on a different interface and it went just fine.

AUHostingService does show high CPU usage (above 100 in the activity monitor) so I tried that now, I turn off the channels by the header components one by one (the sends as well), when all channels are off then it eliminates the problem, if only one channel is on then the problem occur. I tried to playback with only the bass channel on that has only 2 fabfilter plugins on it (pro q and pro c) and it still stutters. I don't think the problem is with fabfilter because they are all running natively. It does happen less often with less channels active.
My audio settings are:
I/O Buffer size: 1024
Processing Threads: 10 (8 high performance cores)
Process Buffer Range: Large
Multithreading: Playback Tracks
Summing: High Percision

I did a small test:
I opened a new project, added 2 audio tracks and sent them to 5 different buses, each bus has one plugin.
I tried it each time with the same plugin on all 5 buses: Fabfilter Pro R, UAD Sound City Studio, Neural DSP Archetipe,
In all cases, it stuttered when the output device was the UCX, but switching to the MacBook's speakers works smoothly.
I tried the same scenario on Reaper, and the problem did not occur while using the UCX as output. So, in my opinion, it has something to do with the integration between Logic and the driver.
I also did not see any errors in the Fireface settings app.

Yes, weadi you were on the right track... :-)

I tested with the trial version of fabfilters plugins pro q and c. Activated in just 2 tracks... In a little project with just 2 SW Instruments - each had both (q + c) fabfilters plugins as fx
-> CPU Load jumps to maximum imediatly
-> Same error popups (with the sample rate mismatch) after 1, 2 minutes
-> Definitely, not a Driver Problem (tested with Fireface 802 DK drivers), as it also happens with Mac Speakers (!)
-> Definitely, the fabfilters do sth weird here...

PS (@orimaz2006):
AUHostingService = M1 (ARM64 arch) Plugins
what i was talking about:
AUHostingCompatibilityService = intel (x86_64 arch) plugins

PSPS:
the fabfilters, (i downloaded latest version) run in arm64 mode, so this is not the cause.

Edit: I used DK v4.12 drivers in my tests. - Just noticed that new DK v4.14 and kext v3.33 drivers were released 2 days ago...

Do you use them?

I personally never used them before - hm... the EQ looks nice and is quite simple.
Please don't laugh, but until today i use (and love :-)) the good old ugly AUNBandEQ Plugin...

I tested it with Logic plugin ChromaVerb. At first it did not reproduce, then I started adding more instances of this plugin.
15 instances of ChromaVerb started to reproduced the problem with the RME driver, Switching to the MacBook's speakers did not reproduce it.
Here is a video with 20 instances
https://youtu.be/AM7XnvcYu8Q

I did follow. see post 25.
Also I want to clarify the reproduction on you end, did you only switch the output device or both input and output device from the RME driver? because I found that I need to switch both to the MacBook's input/output to eliminate the problem.

Yes for me on reaper it worked fine, what I meant if it would work for you on reaper.

The only things plugged into my MBP ports are my UCX directly, MagSafe power, and my monitor. There's still a problem if I unplug the monitor. There are no MIDI devices, no controllers, no hubs, just the RME plugged directly into my MBP. This was tested with no other software in the background. Switching to a different USB port didn't help. Closing all programs in the background didn't help (The UA icon will be present as long as I run Logic, I can't quit this program as long as I have UAD plugins on my computer)
All evidence points to an integration problem between logic and RME.
I contacted support via email, and their response was something broken with my system.
I have 10 years of experience as a software engineer working in high-tech companies. If a client showed me the videos I showed you now, I would try reproducing them in a debug environment and looking for the problem. Instead, I'm to blame for this problem. I'm so frustrated.

I installed v3.31, and it is *better*. It still has stutters, but they happen less often (every 2-3 playbacks instead of every playback), and the mic icon is not flashing.
I hope it strengthens the claim that this is a software problem, not a generic troubleshooting problem, and not a plugin problem.

maggie, you always seem to skip my messages lol
read post 31, v3.31 works better for me, so this is a software problem. I edited the original post.
I updated the support team and they passed it to the developers.
Although I am frustrated, I really appreciate the time you all spent helping me.
I spent 3 days troubleshooting it myself, with the help of the forum, so believe me when I say that I followed debugging principles.

I read your post 31.
but i looks the root cause of Problem didnt change, thus it are 2,3 playbacks more now…

Anyhow. Nice, that your Problem is addressed to the developers now. Hope you get it solved.

Thanks for your Feedback.

The built-in loudspeakers and mic is a 2-channel audio interface, also the Focusrite you mentioned is 2-channel if I remember correct.
Switching from the UCX to the built-in audio is a reduction of 95% of audio channels. From 40 to 2.
From what is posted in this thread the issue appears when system overload due to plugins is happening.
No audio driver is able to overcome CPU overload.
If you want to use a high-number multichannel audio interface you have to adapt your work.
Reduce the CPU load by using other plugins, reduce the song project by bouncing some tracks into one track, freezing some tracks etc. The web is full with coaching videos with hints and tricks. Youtuber Chris Sangster for example is a great Logic supporter.

Please don't feel blamed, it's for sure not my goal to blame you.

Edit :
Another hint, in the Fabfilter plugins there is a feature HQ oversampling, if you have 4x or 8x oversampling ON multiple times it can burst CPU usage.
Switch HQ off for test.

No, there is not way to reduce number of active channels. If you may test with Babyface Pro, it has less channels.... So you could test, if hypothesis that your problems depend on number of interfce channels, is valid or not.

The difference between Logic and Reaper may be in that how effectively they distribute load to CPU cores. One may be better than other. The way p-cores and e-cores are handled also may create difference....

I did try that (and watched many youtube videos about performance in Logic Pro) and it didn't work, and also these settings make no sense:
- Processing Threads to 18 (16 high performance cores) - I have 10 at maximum, and it is not even using all of them.
- Process Buffer Range to Small - That would only make it worse.
- Multithreading to Playback & Live Tracks - That would also make it worse since it reserves CPU for live tracks and not only for playbacks.
I also turned off the camera continuity on my iPhone, but that was after I switched to 3.31 and I don't know if it had any effect.

Right now, as I have been working with 3.31 for the past day, it is pretty stable. I get the occasional stutter, but it is not as severe, and the mic icon is not flashing as before. I can work on my heavy sessions with little interruptions.