Header "OnlineSubsystem.h" cause many random errors

Im following one tutorial for c++ multiplayer with steam subsystem.
I included “onlinesubsystem” and “onlinesubsystemutil” to however when i add only header into c++ file, it cause many build errors:
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.