I am facing the same issue and the problem is inside the transmission: TCU, transmission control unit needs replacement but BMw
will not work on the transmission. They want to replace the whole transmission for a tag price of $7,000. If u r under warranty, u r in luck but in my case, I have to come up with the cash to get it replaced. I also complained to BMW of America . They won't do anything and my car has only 76,000 miles. Go figure.