Application window not responding

[Isar-Spaces]

When running a build, the application sometimes whites out and shows "(Not Responding)" in the title bar, as if it's locked up, but the game keeps running, with the scene rendering and video output not being interrupted.
This happens in Unity 2019.3.7f1, but does not happen in 2019.1.14f1.
Appears to happen for all users on different hardware.

Repro steps:
Create a minimal scene with the unity cam component
Build the application and run it in a window
Click outside the application so it is not the active window and wait ~10 seconds
Observe the window stops responding for several minutes, sometimes recovering eventually

[GYDOVE]

I ran into the same problem, did you solve this problem?