With DX12 on, while trying to multibox, within about 90 seconds, and client not in the foreground will go to a black screen and become unresponsive. Only fix seems to be force closing the effected client via task manager and relaunching, however, often, they black screen again. Reverting back to DX11 seems to resolve the issue. This PC has been utilizing three accounts successfully for months before the update. Happy to provide logs, etc as requested.
PC Specs:
Win 11 x64 21H2 (22000.778)
Intel I7 12700k
GTX2080 (Driver 516.59)