Windows Notifications causing black screen on HDR monitor


I’m using an HDR monitor with HDR enabled. Normally things run fine if a game runs in Borderless Fullscreen mode, but WoW seems to switch HDR on and off whenever a Windows notification comes in or if I use the software controls to change the volume. This causes the monitor to switch modes and go black for about 2 seconds, once to show the popup, and then once again when the popup goes away.

Is this a known issue?

EDIT: Switching to DX11 seems to have resolved this behavior.