Hey Veltrix,
I think I managed to solve the problem on my machine, I tried two things, one worked and another not so much. The first thing that I tried was to install a program called Razer Game Booster, it's designed to turn specific features in Windows off when you launch a game but it also has a diagnostic tool that will scan your system and show up any errors that your system has encountered. I tried running the program and it returned a few errors but the time stamps were wrong so I wasn't sure if those instances were causing my games to minimize.
What I did next was to play my games for a few hours, what a hard afternoon that was haha, until it minimized and straight after I wen't into Windows Event Viewer > Windows Logs >Application, and there I found an error which was being caused by a background process that was a part of AutoCAD, some downloader client nonsense. I got rid of it because I never ever needed the feature and the minimizing has stopped. I've no doubt that you'll have some different issue but this way of troubleshooting worked for me.
Best of luck with it mate.