I have a Dec 20 M3 sr+, and this started happening to me too, about a week ago. Annoyingly, it now also doesn't open more than 1-2 inches, so it's pretty much manually opening, and it slamming shut automatically (with some force). Have booked it in for remote service 3rd Sept. Hopefully they can fix it. Recurring monthly trips to SC are getting a bit annoying now though (had lights, and aircon issues 2x).