When you say "Gatwick" or "Rome LIRF", do you mean default sceneries ? If no, are these 3rd party add-on using SODE jetways, default jetways, GSX replaced jetways ?
I tried doing something similar to what you did, went to EGKK (default), switched to the default Cub, moved to LIRF (default), switched to the FS Labs A320, no problems.