Hello all, after a little advice. Gearbox runs silky smooth on short runs and even did a recent 600 mile round trip which was mostly motorway without issue. However after about 35-45 minutes of local driving(stop start/hilly etc) when coasting up to a roundabout for example when power is applied it shunts quite violently into gear. Box is changing up and down generally fine apart from this.
It has however gone into gearbox overheating mode(holding gear) twice now. I’m going to replace the radiator, gearbox oil cooler and lines. And change the gearbox oil to address this. Is the shunting related to this or a separate issue.
Thanks in advance!

Is it definitely overheat strategy and not transmission failsafe mode ?
Can you read any codes with diagnostics ?
There was a similar X5 issue I believe something like a harsh downshift to first but can’t remember without a google exactly what.