xbox controller not discoverable on bluetooth on windows 10

Hi.

I just bought an Xbox controller for my PC, as an upgrade from my older logitech one.

it is brand new from amazon, Model 1708, Lot date 1840, so only a few months old. Firmware 3.1.1221.0.

I am trying to connect to a windows 10 Professional (Version 1803, build 17134.523) and following the steps with the bluetooth control panel, and pressing the front button to make the xbox logo flash faster, to be discoverable, it never shows up in windows
to pair with. I tried this on my work laptop, and the same thing.

My bluetooth dongle is an Asus USB-BT400

I tried connecting via usb and using the xbox utility to check the controller, which shows me that the buttons work and that there is no newer firmware available for the controller.

Any suggestions as to what I could try?

:)