So I was washing my car today, and I go to start her... Starts fine, push the shifter into gear and bam. Car starts having a seizure, violently shaking and throttling back and forth. I quickly put it into D from manual, where it moved to 2nd and was fine. I got the transmission problems warning on iDrive. I continued driving, and the car would shift 2-4-6. You could not put it in R-1-3-5.
I soon after restarted it, and it ended up stalling itself out a few times before I could quickly slip it into 2nd. I was then greeted with the red cog and "transmission overheat" as well as transmission malfunction.
I brought it to BMW and set up a service appointment, but when I got in it again later to move it for them it was perfectly fine... I am still leaving it with them to diagnose. I'm sure the nasty bucking too and fro caused a few 1000km worth of instant wear on the components.
Did some google-fu and couldn't find anyone else who had the exact same problem as me.