This fixed it. I can't believe this bug has existed for 6 months.
uninstalled the driver under "human interface devices" in device manager
restarted.
I can turn the controller off and on again without restarting.
this is the procedure to produce this bug btw microsoft.
connect wireless controller. turn it off, or let it turn off by itself, try to connect again.
everyone is reporting a brief connection then an instant drop.
didn't matter if installed the "Xbox Accessories" app, whether or not I stopped steam, rolled back drivers to before the creators update. nope. just what this commenter in a thread finally figured out 6 months after a bug was reported.
**** like this is why people get turned off of PC gaming.
Come on microsoft fix your **** please.