Discord overlay won't work on several known games.

So I am trying to make Discord overlay work on games like Rainbow Six Siege, Battlefield 1 and Payday 2, but it won't show on these games. I checked that blog post (Games Overlay 101) and I tried on Minecraft though, and it shows up, but I don't understand why won't show up on other games. I have no antivirus right now (not even Microsoft essentials) so it's not relevant to whitelist anything. I checked that box, when I start a game everyone can see what I'm playing. My OS is Windows 10, and I just reinstalled it today.