Right, I’ve now reverted the config file of my PMDG 737-800 Ryanair livery and surprise surprise, with the rolling cache off all is well.
The thread I read suggested that with the ORBX UK Mesh enabling the rolling cache caused problems. Since I disabled the cache I haven’t had a connection drop and the callsign problem has now gone away. I think the connection drops were causing the callsign problem, and the rolling cache was causing the connection drops. An annoying circle of errors!
I guess it’s the nature of the beast that this sort of conflict sometimes happens, but turning the cache off seems to be the solution. Hopefully if others are having the same issue this will solve it for them.
Cheers.