CppCheck - check included libraries as well

I’ve got a project where I’ve written a lot of libs that are included using

lib_extra_dirs =   ../../CamperOs

in PlatformIO.

When I run

pio check -e debug

it only finds the 16 files in the project source folder.

I would like it to check these extra libs folder too.

I’ve tried

pio check -e debug --flags "-I <../../CamperOs>" -v 

but it doesn’t work. Any clues?

See docs: