Source files w/in addon libs folders with *.mm extension are not recognized by project generator.

[bakercp]

Here is an example of an addon with such a structure.

https://github.com/bakercp/ofxTablet

[Daandelange]

Another addon having this issue is ofxSyphon (3 x .mm files and 1 x .m), and this issue also affects parsing of addons in qt creator.
But it looks like Qt projects automatically scan addon folders from within Qt... Should this be a separate bug report ?

Slightly off-topic, as a temporary (and dirty) workaround for qt creator, you can add the concerned files to your ofApp.qbs files: [] section as such: '../../../addons/myAddon/src/mySourceFile.mm' so they get compiled.