Hi
I would think there is a communication problem between engine control aria network and gear box.
Most likely cause of the problem I would think is that there is a oil leak on the gear box connector causing it to lose contact.
Please get the gear box checked for a oil leak from the back right aria.
When there is,the gear box connector will need cleaning and the connection peace in the gear box will need replacing probably a 1.5 hour job.
While you are in there I would replace the gear box oil sump and the gear box oil as well the sump is the gearbox filter.
Kind Regards
Peter
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BMW Technician
ATA Master Technician 24 years experiance