My XPS 15 9570 i9 is also doing this too, downloaded all the drivers from dell, nothing is working, it's a complete pain, all my bluetooth devices seem to pair, but when they actually come to connect it comes up with the error:
"That didn't work. Make sure your Bluetooth device is still discoverable, then try again."
No matter which device I try to connect with bluetooth this happens on everyone.
I've no idea what the problem is but I would like help too.