Just an update, I took the car out last night and put it into sport mode straight after I started it and after a 15 min drive to a fish and chip shop, no sign of the gearbox flaring etc.
Then I drove the 15 mins back home with sport mode engaged again and it still was behaving... interesting....
I have a 2018 ZB V6 and my transmission does the same thing!
Is there any fix that you guys know of now another year or two has passed?
Many thanks guys.