I have a Dell 2 in 1 3147 and an Atheros WIFI BT card
It worked fine on 8.1 and initially on Win 10 then a week ago after an update Poof its gone no bluetooth
I just spent two days off and on reinstalling and reinstalling drivers and devices again again and again.

I bought a new Intel 7260 card from ebay to replace it

That will not be here for a couple weeks
but after "one more try" I downloaded an Atheros driver for 8.1 and installed it manually
then magically its working now.

Not sure what happened though

One thing I have noticed is paired Bluetooth devices cannot be removed, you uninstall them and windows reinstalls them, this happened over and over, no matter what I did or if I went into the registry and removed the profile it still re-installs?

How can you permanently remove a bluetooth device for good?