Using KbCheck through VNC?

As macOS + PTB is getting more and more broken, I wanted to use my desktop development machine (Ubuntu 20.10) through VNC from my macbook at home. VNC works great, and with a windowed PTB stimuli are quite good for debugging. BUT the problem is key entry. KbCheck doesn’t trigger on normal keyboard input (a-z), only when modifier keys are pressed. I’ve tried to pass devicenumber -1 to -3 to ‘collect’ all devices together. Keys are seen by MATLAB and all other apps, it is just KbCheck that has problems. GetChar does work, but all my code relies on KbCheck in the lab. Has anyone else tried VNC (I’ve tried both the Apple VNC viewer and one made by RealVNC), or have any intuition as to what is going on?