My iPhone 6S works flawlessly. There are two times I have problems.
- When I plug in the phone too quickly it will switch to BMW USB. This behavior isn't consistent, so I'm not really sure what is going on.
- When I forget and have BT off, it will switch to BMW BT. Then it may default to BMW BT for a couple of times until it gets in the groove again.
I mentioned the delete and reinstall b/c, I was having a problem with DirectTV Now. I chatted with support and they wanted me to reboot the router, AppleTV, etc. I told them to pound sand b/c this was not Windows OS. They could see the errors but not why. Finally, right before I ended the chat the guy suggested deleting the app which would also delete the data file/cache and reinstall. That actually made sense. So I tried it and it worked. The data file must have been corrupted.
I would delete both sides of the connection, in the car and on the phone.