All bluetooth related options, including a turn off/on slide bar are missing on windows 10 for me, a Windows-Ubuntu dual-boot user.
I suspected this was an issue with Ubuntu calling the shots and indeed it was. I couldn't find this exact issue on this forum, hence decided to answer this myself.
The issue arises when Bluetooth is turned off via the ubuntu Bluetooth System settings.
If the above is true, then all Bluetooth related options will disappear from the windows partition. Including the ability to turn it on or off or to make it pair with any device.
I couldn't really find a solution (seems to have something to do with the level at which the OSes control Hardware), but a simple workaround is to go and turn on Bluetooth in Ubuntu.