Hmm, I'm not really sure. I know there's an issue with the Meta SDK where sometimes if the users left hand can't be seen it won't properly load the hand tracking models but that typically doesn't cause them to not work at a system level with the menu shortcuts. My only guess would be to try and either restart the headset or turn hand tracking on and then off
Had another go at it, and my hands showed up, and I was able to play. Very nice sound, and the little CASIO keyboard style backing tracks were terrific. Couldn't play more than one-two notes at a time though, so no two-handed play and it limited the utility of finger tracking. That was my first time playing a VR keyboard, so thanks! Seemed like it was in tune, did you use samples for the keys or pitch-shifting? Nice one!