Hello Umberto,
today I started running into a problem when I try to customize a "Parking". No other add-ons out MSFS are running. And I have tried 3 different airport and 2 different aircraft types. Funny enough, I can get a work around by selecting to customize the "Parking System" and edit parking like that. In VHHX I have tried with the A300 and the 737. In TNCA and TNCB I tried with only the 737. All with the same results. I have included the log file for reference.