I'm running a windowed Monster Hunter Rise on one split and forcing it into borderless using the 'Remove Borders, Size to Full Screen' scripted function. After a minute of the game being launched, the DisplayFusion taskbar or taskbars (depending on my split config) disappear as if disabled. When exiting the game, the Windows taskbar takes up the entire monitor for a moment ignoring splits before resizing to the proper split size. Around 30 seconds after this the DisplayFusion taskbar/s will reappear.

I've only tested a few games with this setup but this seems to be the only one so far.

Sure. It's all in here. The DF taskbars disappeared at 7:10PM and they reappeared a minute or so later after I closed the game.