doxygenfunction can't recognize default parameter values

[SigmaKlim]

Hello.
Here I have the function:
void MyFun(int x, char8_t* y = u8"ib")
It is correctly parsed by Doxygen.
However, when referenced with .. doxygenfunction:: MyFun(int x, char8_t* y = u8"ib" ), I receive an error saying " Could not parse arguments. Parsing eror is Invalid C++ declaration: Expecting “,” or “)” in parameters-and-qualifiers, got “””."
I need to include function arguments into the command, so I can't just use .. doxygenfunction:: MyFun. Neither can I use .. doxygenfunction:: MyFun(int x, char8_t* y ), because breathe does not connect xml function declaration with the command. The only solution I found is to completely exclude the problematic parameter value (with @cond/@endcond). This is, of course, undesireble as the reader would like to see the genuine function signature with all the default values and not some "postprocessed" version.
Any suggestions, please?