Serial-Port definitions when building for 1.12.3 not applied

I hope this is somewhat the right category…
When I build locally somehow with 1.12.3 the serial configuraiton defined in the default.cmake is not applied anymore.
Can anyone tell me how to assert when building the QGC-facing ports are taken from there?

correct port assignment taken from my defaults.cmake

incorrect port assignment

I think I might be not very good at explaining my problem so feel free to ask any details… :wink: