I had that problem with my 07 750. It was under warranty, so they replaced some type of electronic module on the transmission and it fixed things. I want to call it the ECM but I can't recall.
2014 M6 Convertible Individual Citrin Black/Champagne Full Merino - 6MT, Carbon Ceramic Brakes, Exec, B&O, Night Vision, Driver Assist, 15% Tint, Coded
2013 750i Mineral White
2011 750i Jet Black
2007 750i Monaco Blue