Disable or edit resolve context

I'm pretty fed up with this IDE at the moment because it ACTIVELY stands in the way of me developing. I have a program that has mixed both C and C++ files. This IDE (specifically designed for C and C++ development mind you) just cannot keep up with that. I have CPP files with a clear CPP extension being resolved in the context of C files, I don't even get the option to switch to a CPP file here. Why is this even in the editor? Why can I not disable it? And why are C and CPP files basically treated interchangably in an IDE specifically designed for C/C++ development? That's like treating Java and Kotlin equally or JavaScript and TypeScript.
In any case, I have now managed after countless cache invalidations, restarts and about a solid 2 hours of googling to completely break it. Deleted the idea file and now the program doesn't even recognize my .cpp files as C++ any more. Instead the context resolves to some C file. I am honestly pretty much done with this and this is a last hail mary to save my project in CLion before I do the sensible thing and switch to NeoVim which doesn't try to be a smart IDE and fails miserably. 

In any case: I use a custom Makefile (another thing I don't understand, why is CLion so obsessed with CMake? Why not let me chose my own build system?) and it's loaded properly. Using said makefile my project builds perfectly fine and runs like a charm so the error is definitely with some weird code inspections in CLion.

Here's it failing to recognize cpp imports and the std namespace

because while it knows it's a C++ project it still tries to resolve some small C file: