Oct 01 2021
The Windows 11 build is 22468.1000. This issue happens in the following circumstance.
1. Start a virtual machine in virtualbox.
2. Run Diablo 3 in windowed fullscreen mode.
3. Switch to the virutal machine by pressing the "Windows" key and clicking the virtual machine icon in the taskbar.
4. Do something in the virtual machine (like open a browser or a terminal). The taskbar will be disappeared and the lower part of the game screen will be displayed instead.
This problem does not happen for virtual machines in VMWare. Also not happening if the game is in fullscreen mode.