Linux Qt Creator - Cannot find API?

I’ve built UE4 from source and setup Qt Creator on my Linux Mint machine with the help of this guide:

So far, compilation and everything seems to work fine, but Qt Creator does not seem to properly recognize the Unreal API as almost everything is marked in red as error. Functions and member variables alike. Includes seem to be fine though and classes (like UCameraComponent) seem to be fine, too. So it’s kind of a mixed bag and I have no idea where that comes from. Code completition also doesn’t seem to work for standard Unreal API functions (like GetCapsuleComponent).

Any idea on how to solve this?