Firstly, thanks for your persisting efforts raising this. It’s one of my top most annoying bugs too when trying to simulate Ops, so pleased there’s this thread!
Just completed EGLL > EGCC > EGLL. I’m still on SU13 and tried with ‘Disable GSX in cruise’ option enabled. Still no traffic parked, or moving at the return airport. So would hope that means it’s SU14 that’s fixed and it makes it to the final release (or a combination of both SU14 + GSX option).
One question, I’ve also noticed behavior where nothing animates, such as Jetways, at the return airport. Did you check if they also worked for you in SU14, at the return airport?