I'm not up on my firmware information but I believe it's not Boot Camp that maybe the issue, it could be the firmware in the card that killed it. It may not of been able be written for both the MacOS, no issues, no problems, it just works, etc, and have the same for the Windows side. Writing drivers to "make it use A monitor" in Windows dependably may have been the only way to keep it stable and to write a dual firmware to support the extras on both sides may have had to many isses?
That's my guess and i'm sticking with it!
OR, it might just be a mater of finding the right drivers.
You might also do Yahoo/Google search as there are many other Mac sites that do quite a bit more in depth work around's and the like.
Contact Apple an let them know things like this, the only way to change it is to make sure they know people want options like that. (Not that it may do any good but hey, you tried! 😁)
I dug through Apples site tofind this. Select Product Feedback. I would definitely use it to express your displeasure, politely, on the dismal Windows support for things that the Mac can do but they won't support it on the Boot Camp side.
****, simply keeping the drivers up to date just to play a bloody game would be nice.😠