Thanks for the suggestions. Regarding number 3: did you activate the option 'Full LC Display Support' under preferences?

We'll check.

Regarding 1: If the input layer is selected, it works how one would expect.  Arm a track, and the submix focus changes to that channel.

However, if the software or output layer is selected, there are more-or-less random changes to the submix focus.  For instance suppose I have the software output layer selected.  Then if I arm channel 1, nothing happens.  If I arm channel 2, all of the small boxes below the channels on HDSPe Mix turn red and say NONE.  This odd-even behavior is repeated until channel 11.  Pressing record arm for channel 11 selects the submix for channels 1 and 2.  Nothing happens when arming channel 12, then channel 13 selects submix focus for channels 3 and 4.  Very strange. 

The Nucleus works as advertised for channel arming in Pro Tools and Cubase, so I think it is sending the proper MIDI.

I recorded the MIDI generated by the Nucleus talking to HDSPe Mix to a track in Pro Tools.

I started with HDSPe Mix in the Input layer and channels 1-8 in focus.  I pressed record arm on channels 1-8.  As you say, I saw C1 On/Off, C#1 On/Off, D1 On/Off, etc. generated on MIDI channel 1.  HDSPe mix correctly selected the the appropriate submix.

I next pressed the down arrow which moves the HDSPe Mix to the Software layer with channels 1-8 in focus.  This generated a MIDI C#9 on/off on MIDI channel 1.  HDSPe Mix correctly moved the yellow highlighted focus to the Software layer channels 1-8.

I then pressed record arm on channels 1-8.  Again, the correct Midi notes on/off were generated: C1, C#1, D1, etc. on MIDI channel 1.  But HDSPe mix did not respond correctly.  It responded as I described in my earlier posting.

I am puzzled by our discrepant findings.  Are you sure you are sending HDSPe Mix this sequence of MIDI events?

It turned out that the current Mac driver was not on par with the Windows version regarding remote support. Please re-download version 2.76. This silent update fixes several missing features and should work now for you.

I am pleased to say that record arm now works as expected in all layers: the correct cuemix output pair is selected when pressing the record arm button.  MC, Thank you for your prompt action on this!

However, metering is still not displayed on the Nucleus control surface.

In answer to Matt Robertson, there are still only 8 channels of control.  Channels 9-16 on my Nucleus remain dark.  I suspect that this will require RME adding the option for a second MCU.  It sure would be useful!

Glad to hear it! 

Now I know why so many people speak highly of RME as being a responsive company!

The Nucleus data (or any MCU based control) is just normal MIDI data.  The way MCU implements channels 9-16 is by putting the same MIDI commands as channels 1-8 on a second MIDI channel.  Currently RME is only set up to read one MIDI channel at a time.  All RME needs to do (I say this with a rueful chuckle since I am a programmer myself and know that these things are never as easy as they seem) is to allow a second MIDI channel to be recognized and route those MIDI commands to their channels 9-16.

My first request would be to get metering working.  That way I can hide the HDSPe Mix window and use my full screen real estate for Pro Tools or Cubase.

It would also be extremely helpful to allow us to have the meters spread out horizontally.  The HDSPe panel takes up a great deal of screen real estate because it is almost square.  Thus, I need to make my Pro Tools windows much narrower in the vertical or horizontal direction in order to keep the HDSPe Mix meters visible.   Almost 1/4 of my monitor real estate becomes wasted space. 

Ideally, I'd like to see the HDSPe Mix meters be half as tall as they are now and have all 3 layers be displayed side by side.

I don't buy the in-line argument in the manual.  Having run interface design teams (google OpenMx SEM if you want to see one of the projects I direct), I have found that if you need to make an argument like that to your users, you almost always are forcing something on them that they would wish were otherwise.  A section like that in a manual is a sure sign that it is time to implement an interface choice.  Of course, I realize that this is not simple.

If the layers were smaller and displayed side by side, I could see what was happening while tracking and have Pro Tools windows be the full width of the screen and almost the full height of the screen and have very little wasted space.  As it is, I just slide the HDSPe Mix window mostly off the bottom of the screen so that I can see only the upper 2/3 of the input layer meters.  Not ideal, but it is the best solution available to me given the current interface.

Thanks for the suggestion.  I'll give it a try!