classes spread over additional files (other than header and source) have their symbols parsed only partially

I have classes that are structured as follows:
.h file contains complete declaration of class members)
.cc file contains definition of all "non-special" members
.icc file contains all inlines, public template methods as well as (if required, methods of template class)

I added the .icc extension to the CppEditor.mimetypes.xml file (I tried to add it alternatively as x-c+hdr and as x-c+src).

When trying to use the C++ navigation functionalities:

• Follow Symbol
• Switch between Declaration/Definition
• Find Usages
• Rename Symbol

for symbols that are declared in the .h and defined in the .icc, these symbols (like methode names) are identified correctly if issuing the above commands over the declarations in the .h file (i.e. the corresponding definition in the .icc file), but trying to do the same with the corresponding symbol in the .icc file does nothing.

The "Find Usages" behaves erratically when issued from an .icc file. Sometimes it does nothing, some other times finds most uses, but not those in the current file etc. The particular behavior is reproducible for a given symbol, but I couldn't tell what makes symbols trigger these different behaviors.

I tried to rename my .icc files to .inl but the behavior stays the same.

Attached is a micro-example that shows the (mis-)behavior explained above.

Thank you for an extraordinary work environment.