I think that's exactly what happened, maybe rollback to previous drivers to see if it resolves the issue?
I am using a Maximus IX Code BIOS 0906
Windows 10 Home 1703 (OS Build 15063.447)
Qualcomm Atheros QCA61x4A / driver version 10.0.0.285
BCM20703 Bluetooth 4.1 USB Device / driver version 184.108.40.2062
Often my bluetooth headset will just turn off and the system will say 'bluetooth disconnected' in Setting/Devices/Bluetooth, the toggle to turn it on or off will no longer be there and the only way I have found to get it to show up again is to shut the computer off, unplug it from wall power, then replug it in and reboot.
This happens without any warning (mid youtube video for example)
I just did a power cycle on my machine after reading the kavanavak's response and my bluetooth comes back if power is pullled from the machine. I normally only do restarts and shutdowns but not a power cycle. I will keep testing to see if I can get any more info.