I have the same problem since using the SU10 Navdata API, every flight I made since the activation GSX works fine on the departure airport but wont load at the destination airport. When i hover over the taskbar, the couatl logo disappears. My guess it closed itself some time during the flight. When I manually open the couatl by "Start Couatl for GSX MSFS", GSX works again.
Best,
Alex