Sometimes no TV ?

[Muz]

I had a transmission update a couple of months back and now, my TV function has changed. When I stop I cant get any TV after being parked for 10 minutes or so, instead all I get is the NAV map I get sound but no picture.. and I've tried retuning and all the settings

However after going back to the car after 20 mins or so the TV function is fine ?

Have they put some delay into the system or what ? since all you used to have to do was put it in park and the TV worked fine, then when you moved the pic went off but the sound stayed (but I never saw the nav map when you called up the TV function)

Any ideas ? or is it another trip to the dealer