I don't know if it's related or not, but if you installed an A2A plane, then you might want to ensure the SimConnect interface is installed correctly, since the P3D installer tends to forget that often.
Or perhaps you did that manually already ?
It consist of going into the root P3D folder, then "redist", "Interface", "FSX-SP2-XPACK", "retail", "lib", and then execute the simconnect.msi file that's in there.