Same issue here. Fresh install of both P3d v4.2 and F50.
I load the default scenario (F35 engine running) then change aircraft to the F50. Electrics are on, I get the intro window showing me how to manipulate the knobs, click spots appear to be working (I can hide the yoke), but FMS is off.
If I change to 2D panel I see a window telling me the Navigraph database is being built. There appears to be a progress bar but nothing happens (left it there 30 minutes).
No antivirus except Windows Defender. I opened the Windows Defender Security Center, went to App & Browser Control, put Check apps & files to Off, reran the installer but no joy. Also tried launching P3d as administrator, same result.