Do you have the same issue if you follow the OP’s steps to reproduce it?
CONFIRMED - it has always been like this.
Also, even on a Single Monitor, if an Instrument Display is popped out, then interacting with that popped out windows, with the mouse , to MOVE the window, also freezes the SIM, while Drag Focus is on that window.
Provide extra information to complete the original description of the issue:
If relevant, provide additional screenshots/video:
CONFIRMED