Fusion 12 blanks the screen when sound happens

[Neil_Erskine]

Using Fusion 12 on Big Sur, I run a Windows 10 virtual machine in full screen mode on a DisplayPort monitor.  Whenever a program does something to make a sound happen, after I have pressed ctrl-G return at a command shell prompt for example, the sound occurs but is then followed by Fusion bringing up the spinning circle, and then blanking the screen for a couple of seconds.  This is very disconcerting, and did not occur when I ran Fusion 11 on Catalina.

I tried setting the sound output device to each of the available options (internal device, Display port device), with no difference other than where the sound comes out.

Any ideas?

MacBook Pro mid 2015, 16 Gig memory, Core i7 processor.

[Neil_Erskine]

At least once a period of time passed during which the temporary blanking and re-presentation of the screen occurred cyclically on a schedule of perhaps 5 seconds between instances. I flailed about trying this and that and the problem stopped after a few minutes.

[Neil_Erskine]

The problem recurred after a short while and persists.  The problem is not related to multiple VMs running at the same time, as this happens even when only Windows 10 VM is running.  It becomes worse over time.