Did you enable Windows compatible WDM devices in driver settings?
See also:
https://forum.rme-audio.de/viewtopic.ph … 57#p215557
I wouldn't use Windows Mixer, use TotalMix FX.
In RME driver settings, enable the WDM driver only for I/O ports, that you really need.
E.g. where active monitors and headphones are connected to.
Then they are dynamically being created and visible in Windows Sound.
There you can make them to the Windows default sound device.
At that point, you do not need Windows Mixer anymore. Use TotalMix FX.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14