You're not removing the profile in the head unit if you're doing it while driving. You can't, or maybe shouldn't be able to do a navigation reset while the car is in motion.
Sounds like your just removing the profiles in your phone.
There's the BT profile in your phone, one in the Navigation/Head Unit. If either of these is corrupt it will cause issues. They both need to be completely removed. That's why when some people rename the phone the issue goes away, some head units pair profiles with phone names. So, if you rename your phone the head unit will create a new profile. The head unit BT controller thinks this is a new device and assigns a fresh, spankin-new profile to the "New" phone.
If you load a new, or get desperate enough to make the mistake of loading a beta OS on your phone, you might think the iOS update fixed it and this probably isn't the case. The BT profile on the phone changed enough to trigger a new BT profile within the car because the new update. Then guess what? Same exact problem and you spin 'round and 'round again when you could have started by resetting the Navigation/Head Unit and reset your phone and you'd be back on the road in 20 minutes.
This is very common in BMW's due to the lack of redundancy checks in the system.