That is weird. An operating system and driver should not allow an application to do that. I do not experience this problem on my Windows 11 system NVIDIA GeForce 4070. In fact, I can use the Shotcut and the timeline just fine after moving it to another screen or back into the main window. Also after swapping which window is on which screen. I think that says something about the quality of the drivers. This is a bug in your AMD driver and nothing I can fix in Shotcut. Please report it to AMD.