Hi @charles_piano and @mcfarlandjp, yes indeed, looks like the other case that I had in the German forum. The odd behaviour started with the 25H2 Windows update but it actually turned out to be a Focusrite driver issue. That other user has a Focusrite Scarlet that he also used for MIDI interfacing. Connecting the MIDI keyboard directly to the computer solved the issue for that person.
@mcfarlandjp , please try to disconnect your Focusrite (if you can connect your MIDI keyboard directly to your computer), does the error persist?