There seems to be an issue with DisplayFusion preventing my game (Overwatch) from being maximised after an alt+tab intermittently. I need to keep retrying until it randomly works. Closing DisplayFusion fixes the issue instantly.
What's interesting is the bug happens mainly when the game itself enters a match. It works fine when in queue / menu. Probably something to do with the Graphics card kicking in?

EDIT:

Not sure how material this is, but I have DisplayFusion taskbars appearing on both screens, replacing the default windows one

Here you go Owen!

Thanks Owen, that has fixed it for now (basically same as turning DF off) but its not exactly an ideal solution. I do have itchy fingers and alt tab quite a bit in queues and stuff.

Do you know the root cause? Is this something that can be fixed in a future build?

Disabling hooking doesn't seem to change the outcome

That's correct. I will note that I've been a long time DF user, and this issue only started relatively recently. Was there a DF update?

Otherwise the only other thing I can think of is that I did force DF to be on both monitors and also ungrouped the buttons.

Disabling on Primary seems to also fix it. I guess DF is trying to steal focus over the primary monitor when its enabled...