IDE highlights most types RED (unknown typename) but finds the declaration with "go to declaration"

Hi,

For some reason, Clion highlights most types in my project red (unknown type name). However, when I use the "go to declaration" function, it finds the correct declaration of the type in the correct file. So it knows where the declaration is but somehow displays it as unknown in the use-site. If it can find where it is exactly, why would it use incorrect highlighting? The project compiles and runs fine. This seems to have regressed when I updated to 2018.2 or maybe I'm using the new version incorrectly. I'm happy to upload the project somewhere.