Hi. I am by far not an expert on tis particular topic, but I'll offer a thought that may not help solve it but might help where not to look.

My wife has an even older Clavinova than yours and it works fine into BIAB, although it isn't practical for me to test it now with version 2025. MIDI is such a simple signal over a slow serial port that I suspect that is not the problem here. The structure of MIDI signals has not changed in all that time (MIDI 2.0 isn't really implemented just yet). Nor to my knowledge has anything about handling MIDI changed from Windows 10 to 11, as you tested.

If you can get users Gary Curran or RHarv to see your post, that might help. And if it does turn out to be a problem in version 2025, we can alert the developers.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.