I have 2 small HDMI touchscreen monitors (480x480 resolution) connected to the 2 raspberry pi 4 HDMI inputs. I have these these monitors duplicating a single display. Touch input on each device maps to the UI elements which are clicked. However, while one monitor renders everything as expected, the other monitor renders only the desktop image, desktop icons, and will NOT render active windows. If that window is being dragged it WILL render on both monitors but once the mouse button is released and the drag event ends, the window disappears.
For example, if you were to open a shell that shell would appear on the first monitor but not the second. If you were to drag the shell it will appear on both monitors until you release the mouse button and end the drag.
Could someone help me with this? I've tried playing with xrandr commands to no avail. I've tried server reboots, switching cables around, plugging in the devices after boot, booting with devices plugged in, unplugging and replugging devices after boot. None of this has changed what I've described here.