QtCreator 4.9.0 - no semantic highlighting with clang code model

[CybranII]

Since updating to 4.9.0, I have no semantic highlighting for C++ header and source files in QtCreator. All code just stays black. Semantic highlighting works as expected if I disable the clang code model. Platform is Windows 8.1 x64.
Is this a known issue? Is there any solution (except for disabling the clang code model)?

[J.Hilk]

@CybranII
I have that from tome to time as well, a QtCreator restart usually fixes that.

@aha_1980 also something for the clang code model error list ;-)

[CybranII]

Update: The same thing happens on another PC, with the same project. Also tested another, way smaller C++ project - semantic highlighting works there! Restarting QtCreator has no effect. The highlighting worked for the problematic project with the older QtCreator version 4.8.x.