Thanks, Tim. It appears to be working properly now.

I have installed Plan G v3.1.1.94, and let it build a database for P3D v2.4. This process seemed to proceed normally, and I set the Prepar3d.exe and scenery.cfg locations correctly. However, the database does not seem to be complete. I only have a relatively small number of UK airports and airfields visible on the map (I only generally fly in the UK and Ireland), and if I try to use "Quick Plan", most of the airport/airfield ICAO codes that should be available to me are not working.

Can you please help me to resolve this issue?

I have attached the log file.