One of the issues with Windows Mixed Reality is at times you will be told that your headset is not plugged into a USB 3.0 port. You’ll get an error message like “Check your USB cable” or “Something Went Wrong We’re not sure what’s up, but this error code should help: 2181038087-5.”
If you check the /R/WindowsMR subreddit there are a number of suggestions like using a powered USB 3.0 hub (which I still intend to do to extend my cables) or checking to make sure your USB 3.0 ports don’t power down and other esoteric stuff like that.
What I’ve been doing that seems to work is rebooting with my headset completely plugged in. As soon as I log into Windows 10, I go Start->Settings->Devices. If it’s not listing the headset as USB 3.0 I reboot again. If it is listing as USB 3.0 I open the mixed reality portal and will still sometimes get the USB error, but typically if I unplug the USB cord and then plug it back in after waiting a few seconds it will come right on. Good luck!