Cargo and catering services are not available.

[choi yoon ku]

At cargo and catering services at GSX-supported airports, car and catering vehicles are waiting for service.

However, the message of GSX is a message that opens the service door and cargo door.

The door opens through the FMC of P3D, but the messages are repeated repeatedly and they do not carry the cargo's load and catering.

Please tell us how to fix this problem

[virtuali]

You don't say which airplane you use, and if it's a supported one.

Since there's no such thing as a "FMC of P3D", it looks like you use a 3rd party airplane so, it must be correctly configured, if it's not already internally supported by GSX and, if it's not correctly configured, GSX cannot recognize if the doors are open or not.

[choi yoon ku]

I am using the PMDG 737NGX model.