The issue has been present since beta 6.
This discussion deals with the issue on beta 6 but is marked as resolved.
Well, 2 betas later, it is not.
Fusion 12, whose main feature is compaitbility with Big Sur, is currently unusable with Big Sur.
Please only mark this question as resolved when it works.
I apologise for the confusion, but I marked this issue as "answered" in my original thread, not because the problem has been resolved, but because VMware has stated the root cause lies with Apple and they're awaiting an update to macOS Big Sur. As are all of us...I can confirm that the latest Beta 8 release did not resolve this issue with my MacBook Pro 16".
Ah the perils of running beta software on production machines....
Have to say, Big Sur seems to have a lot more regressions than usual - does not bode well for things as complex as Rosetta. I'm usually one to upgrade fairly quickly after GA, but think I may just sit this one out until .1 or .2.