Bluetooth in car stopped pairing with phone, any ideas?

Firmware update on both and try again.

I second what he said. My car has done this a couple times. Pain in the arse but reversible

Ford Sync systems tend to do this from time to time as well.

Pulling the Sync fuse for a minute usually does the trick. Maybe try pulling your radio fuse if all else fails on the BMW.

Reset network settings on phone. That’s how I fixed mine.