LinuxCNC on Raspberry Pi 4

Hey Danny, in your config.txt , try changing your graphics driver from kms to fkms
That was the issue for me at least, when my always rpi screen didnt work with a new image.

dtoverlay=vc4-fkms-v3d

Hmmm... ok, that made it WORK on the Onn monitor. But the Motorola HDMI docking station just went dead. No-signal instead of a slanted screen.