[PhotoDoc05]

Geoff, Thanks for posting those remarks from Klaus! I went through all those steps.

I have a PSR-SX900 connected to Win11 desktop running 25H2  But, I use a Roland UM-1 adapter using the MIDI ports on the keyboard, going to USB on the PC.
What I've noticed, is that in MobileSheets (3.9.34) under MIDI settings > Configure MIDI Connections did not show any Input or Output devices. The MIDI device showed Genos PSR.

Under Windows Services, Windows MIDI Service, the Startup Type was Manual (Trigger Start), however, the service wasn't running. This seems to be the crux of the problem.
Changed the Startup Type to Automatic (Trigger Start), did a complete Power off Shutdown, started again, and now MS was recognizing the MIDI ports, and working correctly!

Regards, Good Luck,  Jerry

[Tiasdad]

Try using a midi monitor program. I use MidiView which opened the 'closed' midi ports and gives the option to select the Digital Keyboard in & out devices.

It doesn't solve what is a Windows issue but it is an easy work around which doesn't involve deep menu diving and adjustments.

Hope that helps, for now. Have fun :o)