This is about hardware, not software, but you had no correct sub-forum for this, so I chose this at random.
Just like this guy, I have issues trying to connect a Microsoft Sculpt Comfort Desktop keyboard (2012), but the main difference being that I need to connect it to other operating systems (macOS and Linux). I have the same underlying issue: I cannot find a way of explicitly making the keyboard initiate a pairing, which makes it impossible for other devices to pair with it. To make matters worse, Microsoft supplies no real manual for how to connect with this thing, so there is no reference for how to do this. I envision that the keyboard might have some kind of key combination that will trigger pairing, as there is a lot of unusual symbols on the keyboard that I have no idea what means.
The supplied dongle, which one can use when you do not have built-in bluetooh, does have a button to initiate pairing. After failing to connect with my Mac's built-in bluetooth, I tried that. That also did not work.
Could there be other issues at work here? I wonder about power supply
I replaced the batteries with fresh new LR3's. Momentarily, the power light came on for a few seconds (full green bar), before going away after a few seconds. I suspect it powers down when it has nothing to connect to, but this is probably where I would need to start pairing, right? So how to do that?
Almost success?
Sometimes - I cannot replicate it consistently - I somehow manage to trigger the Keyboard configuration of macOS. I think these are the steps:
1. Take out the batteries of the keyboard (to "reset")
2. At the same time, insert the batteries and press the connect button the USB dongle
3. Hopefully, a keyboard configuration dialogue should pop up, and once you say "Next", ask you to press the button right of the leftmost Shift button (in order to identify the keyboard).
It is here the process stops (if I at all manage to trigger it). The keyboard seems to have powered down (no power light) by now and there is no reaction to be seen anywhere.
***Move from Gaming and Xbox / Hardware and network / Controllers and accessories***