Solution for those trying to connect Bose bluetooth headphones
I own Bose QC35 II Bluetooth headphones. They were "Paired" but not "Connected" or recognised as a audio device. Like others, I scoured forums trying to find a solution. I wanted to post a potential solution that worked for me, and I hope this helps many others. I found most of the solution in this post:
After updating Bose software and "pairing" the headphones, unplug your headphones from the USB cable.
You need to go to Control Panel> View Devices and Printers. Double-click on your headphone device (mine was under the "Unspecified" category). Click on the Services tab. Here you should hopefully see a menu for Bluetooth Services with checkboxes and services like "ARfcomm", "AudioWear" and "Remote Control" etc. I didn't know which one to tick so I ticked all of them.
Click apply, wait for services to load. Close window. Your device will hopefully magically appear as a headphones or speaker symbol in the Devices and Printers window under "Devices".
Now go back to your Bluetooth settings windows (where you originally paired your device). Hopefully now your device is classified as an "audio device" rather than "other devices". If not, try disconnecting and pairing again. I may be missing a few steps as I was frantically troubleshooting but I hope they are easy to figure out.
I hope this helps some of you that have spent lots of money on these great headphones!