CLion issue with include autocompletion

Hello,

I have noticed lately (first time it annoyed me two months ago), that CLion stubbornly ignores my header files, while not minding system includes. Let me show an example:
 CMakeLists.txt:

Yes, there are three different types of includes, and whichever I choose, it does not autocomplete anyway, and here is code:



In case of doubts:



And after random thought, I found out the issue. It does not understand what "hxx, txx, or EVEN cxx" files mean... I am profoundly confused. Is there any way to associate these files??? I got extension files set correctly, as seen underneath:



My friends can reproduce it, so I think it is a bug...

Excuse my language, and thank you for the help!