DFR0550 Screen was working on 2 Pi4 B but after OS update only white screen but touch still operates

Hi

I have a 5" DSI touchscreen. When i initialy got it several weeks ago i plugged it in and tested it on both RPi 4's and it worked straight out of the box. Over the next few weeks i updated the OS on the pi's. Now when i plug the screen into either of the pi's it just comes up white and never changes but if you touch it your finger movement will move the mouse on the main HDMI screen. Then when you shut down the main window divides its selfup into a set of frames around 800 x 480 (the resolution of the touch screen). It looks like an overlay problem, i.e the overlay is being applied to the monitor instead of the touchpad. This occurs on both Pi's, one is 3 years old and one is 3 weeks old.

Does anyone have a solution to this issue?