Mouse functions not working?

So, for sending keyboard keys it seems fine. However I already had a program capable of doing that, and got this because it claimed to be able to send mouse clicks across multiple programs/games.

I tried this with 4 copies of a game,  and it was.. very unreliable. Sometimes it would double click, sometimes it wouldn't click at all. And this was on very simple tasks, just attempting to click a single icon on screen without any movement or anything. 

I thought maybe the game was just causing issues, but I can't seem to get the mouse function to work correctly no matter where or how I use it. Even just running 4 copies of Calculator, all on the same monitor, it doesn't send the mouse clicks at all. 

Is there some simple fix I'm missing? I've tried using the maximizer, not using it, running as admin, different programs,  etc etc.