In services, try to set the Bluetooth Support Service to Automatic instead of manual.  I did encounter this issue, but my was because one antenna came loose, but this is issue can software related.  Worth troubleshooting first before opening the laptop to check the antennas.
 

I had this happened to me in device manager you will see"unknown something something " i had to is remove the wifi card from the laptop and than boot windows than shutdown reinstall the card to this day been working fine.

I suspect I have a hardware issue, and hopefully fiddling with the antenna or uninstalling/reinstalling the card will do it like it did for you guys.
 
I checked the BT service, and it was set to Manual, so I put it back to Automatic, and even manually started it. No change. (If the device actually disappeared, maybe Windows decided to turn the service back to Manual, kind of makes sense.)
 
I updated the drivers from the version Microsoft provided (18.something) to the ones in the @vistarshook link. The installation went fine, but the Device Mangler still shows the Bluetooth device in the "hidden" area, and reports it is disconnected. 
 
Does anyone know of a guide for cracking the case and manipulating the wireless card? Won't be my first rodeo, but I'd certainly like to have some pictures to refer to for my first time working on this model laptop. 

Unplug from AC, and also unplug the battery, to the right of the SSD.
 

Just the two screws in the rubber "feet" are hidden, but has a torx screw driver entry for it.

Haaahah!
Today I let the battery run down too low, and the machine went into hibernation. 
As sometimes happens, it didn't wake properly from hibernation, so I was forced to do a hard power reset. 
When it came back up... Bluetooth was back. 
¯\_(ツ)_/¯

The battery connection pulls all the way out. At least mine did. I don't remember needing to release a latch.

I was wondering the same thing. Thanks!

ShaunMurphy
Same thing happened recently to my sc17 as well. Bluetooth no longer appears in the device manager (even under hidden)... reinstalled win10, evga drivers and still no bt. Updated to latest Intel drivers but no love.
 
Still investigating

dude do what I did just remove the WIFI card physically from the laptop and srtart it login to windows and than shutdown reinstall the card and you all done :)

Arrghh! Thanks for posting that info. My bluetooth has been broken for a year, and I'd also tried every software option to try to fix it. As also reported above, the Bluetooth portion of the AC 8260 appeared in device manager as an unknown USB device that failed to enumerate.
 
Disconnecting the battery did not fix it, but removing the AC 8260 module, booting with it removed, then shutting down, plugging the module back in, and booting fixed it. 
 
 

HaloTechnology

g_christopher
Arrghh! Thanks for posting that info. My bluetooth has been broken for a year, and I'd also tried every software option to try to fix it. As also reported above, the Bluetooth portion of the AC 8260 appeared in device manager as an unknown USB device that failed to enumerate.
 
Disconnecting the battery did not fix it, but removing the AC 8260 module, booting with it removed, then shutting down, plugging the module back in, and booting fixed it. 
 
 

FYI if happens again to you you dont have to remove it , I found out you can press the tiny reset button above the power button JUST BEFORE Windows Shuts down !

My bluetooth also randomly disappeared last week. Pressing the little reset button (on the bottom of the laptop) just as it shutdown worked for me!