Re: odd diehard (such as Wiley Fox) are doing their best to update phones.
Sadly, this off- and on-against fsck'ing with the Bluetooth stack has been an ongoing PITA since Android 4.3 (maybe even marginally) earlier. Even between minor updates behaviour would flip-flop from working to/from no-working. I'd love to get myself Bluetooth handsfree et al for my car, but really aren't keen on the crapshoot of now-it-works-now-it-doesn't.