Hi buddy,
Finally I reproduce this in my test environment. It does not always reproduce ( 2 of 5 attempts ). I will discuss this with dev.
PS. Personally I want to learn more about your user scenario. So you need the guest always display on 3 monitors ? I know it is not convenient for you to re-enter fullscreen mode and go back to 3 monitors again. But why this is serious for you ? (Just personal interests)
Thank you. 