Cannot select Bluetooth device from Sound Output On OSX Sierra, I can no longer select a Bluetooth Audio device for sound output. I can see the Bluetooth head set is connected and I can select momentarily under Sound Output (see attached screenshot). However, within a few seconds, the Bluetooth device de-selects itself and reverts back to Internal Speakers.

A few notes:


I have tried a few different Bluetooth headsets and none pair with my Mac. They pair with my iPhone and other Macs so I can rule out an issue with the headphones
I have tried deleting Bluetooth plists and re-pairing. That did not work.
I have tried deleting plists related to audio with no luck
yes, I've rebooted my computer.


This strikes me as an issue with core audio but I'm not sure how to address this without re-installing the entire OS
I will add the answer. 

Looking through discussions.apple.com, as usual, yields bad advice: reset, reformat, disk cleanup. Essentially do a bunch of random nonsense until the problem sorts itself out.

Before you do anything overly-complex or even irreversible. I recommend you try what I call the monkey's gambit:


Unpair
Forget Device
Pair
Repeat steps 1, 2, 3 a lot


(Look through comments for specific instructions)

Even when it seems like it's doing nothing, keep doing it. It took me 4 or 5 tries. I was nearly convinced it was the hardware, but then all of a sudden I'm back to listening to mediocre music on a pretty good bluetooth speaker.

This might have been expedited if I rebooted my computer, but I really didn't feel like doing that.

TL;DR please do not reformat or reset your computer without running the monkey's gambit for a while; it might save you a more major headache.

To be fair, this worked for me, but it is entirely possible your system is in a state where this will not help it. I do feel compelled, however, to claim that if you can see the device connected in the bluetooth menulet then it is probably not a hardware problem.