I have a 2012 BMW Activehybrid 7. A few months ago, the car began dropping bluetooth pairings. I would add the phone(Samsung Galaxy Note 5) again and it would drop calls and then the phone wouldn't be listed again. I read on some blog that you could get the problem solved if you signed up for Connected BMW. I started the process and when I input my VIN the webpage said I needed to call the 800 number which I did. There they told me I needed to take my car to a dealer to see if I could have a new part installed. Not a happy camper since we just bought my wife a 2018 750i.
Long story short, saw another post where I was directed to get a software update from the website for my model car. I downloaded it to a thumb drive, inserted in the USB slot, went to settings-software update. 5 minutes later, everything is fine and my confidence in BMW is restored. Don't usually post but this was so aggravating, I thought I had to share what worked for me.