If you put it into R quickly the car stays in neutral. Next time just try to wait a second or two before putting it in R. It's normal..
///M3 Mods: | Eisenmann Race Exhaust | Primary Cats Delete (TTP) | ESS Tune | 19" Advan RS | Eibach Springs | MS Air Filter | BMW Perf. Spoiler | BMW Perf. Splitters | Euro LCI Tail lights | Angel iBright v.3.0 | 20% Tint | Matte black Kidney Grills | CF Side Gills | Painted Reflectors | Black M3 emblem