Getting Black Screen on Bootcamp after upgrading to macOS Big Sur 11.6

Hey all,

I have an iMac Pro 2017 (3GHz 10-Core Intel Xeon W with Radeon Pro Vega 56 8GB) and since upgrading to Big Sur I'm encountering a black screen when trying to boot Windows 10 with bootcamp (it previously worked fine with Catalina).

• I hold OPTION after chime
• Click the new diamond Windows drive
• I get the password screen and windows screensaver (e.g. beach picture) with date (which is accurate)
• It's connecting to my network connection
• Keyboard and mouse both seem to work
• Then blackscreen with cursor

I've tried resetting PRAM/NVRAM and tried SMC reset...Didn't make a difference.

Saw a suggestion to remove atikmdag.sys in the Windows/System32/Driver folder but it doesn't appear to be there.

Also tried shining a torch on the screen and turning brightness up with function keys - it really does appear to just be a black screen.

Any help would be massively appreciated.

-Stevic