This is quite an unusual behavior you got there.
At first it looked like your controller is somehow mapped to
ALT+TAB when you're trying to use it. And it is good that you described how Ori and The Blind Forest react to your controller, because this game works as usual when you
ALT+TAB, but when the game lose focus to some other process or window - it goes windowed mode. So, pushing from that fact I can assume that your controller triggers something in Windows, which it, for sure, should not do.
So, here's what can possibly be wrong:
- You have a fake controller. They appear from time to time even in huge stores with high reputation, because guys from China really mastered doing authentic-looking controllers (same problem with DualShock), sometimes you can't tell it's fake until you disassemble it. So, if no warranty (if you have some; if you do - bring it to service) will be voided upon opening it you should try it and compare with official repair guides if the inner part of looks like original one.
- There's something on your PC that reacts to controller due to which games lose focus. You should check Windows Process Explorer if there's any unknown processes there. You can also check the process file
Right-clicking it and opening containing folder. Also, try to reboot your PC, then open up PE and try connecting and pushing buttons on your controller to see, if there're some changes in processes.
- You've mentioned that you've completely reinstalled your drivers, but still the problem may be here. Though I can't figure out what to do with it.
- And, finally, you actually HAVE some button-mapping software (or driver) on your PC not knowing about it.