The "Foreground App" Volume Hotkeys have strange behaviours in some Games

[fubaWoW]

Hi there,
The Foreground App Volume Hotkeys act weird in some Games!

Example:
If i try to change the Volume of a Foreground App with the set Hotkeys, it does nothing until i Alt+Tab (or Win-Key) out of the Foreground App, then the OSD Appear.
But it does not Change the Volume of the Foreground App!

This happend mainly with Games that run in Exclusive Fullscreen and/or Borderless Fullscreen Mode.

BUT this does not happen on the Application Volume Hotkeys, means if i set a executable to a specific Hotkey it works!
Tested both with the same and also many different Hotkey combinations, all the same!

Maybe there is something wrong with the Hotkey or Keyboard hook?