I have exactly the same issue after landing. I also have this issue at the start of the flight... Not sure what to do? I restart Couatl64. Still stuck at GSX Menu loading, please wait. Even tells me at the Couatl64 Icon in the Task Bar that the Airport Cache has loaded successfully.
I have managed to only to get it going after setting up my FLBW A320 for take off and I'm able to use the Pushback from the GSX Menu.
I tried uninstalling and I and I thought it was fixed then it started happening again. Will try to re-install again.. (Was working ok, not sure what is going on?)