Can also confirm sound bug still on PTR. Maybe this is a bug from windows hence no fix yet from Blizzard. Microsoft just released this for insider ring last week.
February 24, 2021—KB4601382 (OS Builds 19041.844 and 19042.844) Preview
In notes it states - Updates an issue with screen rendering after opening games with certain hardware configurations. (Is this the issue we are having, vague info)
I have just installed and will test today and report back later if it works, fingers crossed