Edited to add result: Store FINALLY took it back. It is a known problem, and I’m not going to take their suggestion to “just use a wire” for a brand new WIRELESS controller, because that obviously defeats the purpose of a wireless controller.
They came out way ahead - I used to refund (and more) to buy 4 more wireless security cameras.
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Finally figured it out - when Microsoft pushed a security update for windows, it killed the ability of the wireless dongle and controller to pair, because it wasn’t being done securely. They didn’t kill it intentionally - both the dongle and the controller are still seen by the OS - but the dongle is not secure enough any more. There was no update to either the controller or dongle - brand new controllers right out of the box that have never been plugged in simply wouldn’t have been able to receive an update prior to being paired.
Which means (a) it is no longer Windows Compatible, and (b) it should no longer be sold, since the claim on the box that it works with Windows 10 isn’t true. The product needs to be recalled.
So, tomorrow will be the last try to return the one I bought 3 days ago - after that, it’s small claims court against both Microsoft and the merchant (which is crazy, because I have almost $3k of stuff I’m waiting for them to get so I can upgrade my system with another Arc, 2 65" Smart TVs as side screens that I will mount in portrait orientation, 2 VESA carts, and I would have bought 2 Logitech controllers if I hadn’t been so soured on the whole controller issue).
But like many of you, I’m over 65 and have time to go to court to fix this shoddy treatment.