Hyperpixel4 has large white rectangle on left side

I have been using my hyperpixel 4 for several days on my pi 4 and the first day it was perfect, but now there is a strange white rectangle taking up about 25% of the screen on the left side. It overlays over windows and you can’t click through it (to the menus underneath for instance) wither with a mouse or touch. The touch works fine. When I rotated the screen inverted the white rectangle came along with the rotation. Rebooting doesn’t fix it either… Strangely I can drag an application window over it (so it only affects the desktop layer). I tried switching backgrounds with no effect.