Header "OnlineSubsystem.h" cause many random errors

Hello,
Im following one tutorial for c++ multiplayer with steam subsystem.
I included “onlinesubsystem” and “onlinesubsystemutil” to game.build.cs however when i add only header into c++ file, it cause many build errors: https://i.imgur.com/YZhxCYp.jpg
Do someone know what cause these problems?
Any help is very appreciated. Thanks.

Okay, after like 10x restarting editor and visual studio, i got it working… i changed nothing so its probably some strange bug.