Include files not added to new source folder.

I created a new source folder in my file stucture, so I have the usual Core and Drivers folders, plus the FreeRTOS folder added by CubeIDE, then I have my App folder. See below.

When I compile this, it compiles the three folders the IDE created, but fails on my App folder by not finding included files. When I look at the generated subdir.mk, I can see that there are indeed no "-I" include statements attached to this folder. Why is this not generating properly for this particular folder and how do I fix it? I'd rather not make my own makefile structure as this is generally pretty well defined, but I can't seem to find a setting to make this work.

Thanks,

Jamie