I spoke with our senior transmission guy (30 years on MB transmissions) and our MB SPOM (factory warranty rep). They both said it sounds more like a valve body issue than anything else.
The MB guy suggested that your tech rep contact the Mercedes tech reps in Montvale, NJ. We've been using that transmission for years and have it sorted out pretty well. It's still somewhat new to the Chrysler guys and communication between the two companies is spotty.