Suggestion: Looking for Group Support within xCloud App

Disconnect and then reconnect your Xbox controller. Sometimes, reconnecting the device can help the app recognize the change in input method.

Besides, close Fortnite and the xCloud app completely, then reopen them. This can often resolve temporary glitches.

Also, it's worth looking for any settings within the xCloud app that pertain to controller use. Ensure these are set correctly for using an external controller.

I would suggest in addition to those steps, looking for autistic support forums and gather groups of similar people

If you've not already tried Deleting your local groups. I'd suggest giving it a shot.

First open up 'My Games & Apps'. Proceed to go into the 'Groups' section and then scroll down to the 'More options' section at the bottom. Proceed to then select 'Delete all groups'. You'll be shown the options to 'Delete all groups' and 'Delete local groups'.

Deleting local groups will remove and then resync your groups information stored in the cloud. Deleting all groups will delete the groups saved on your local console and within the cloud as well. You should then be able to start from scratch with how you
setup your groups..

You have to do it from the gamepass app

Also have to be in an xcloud region

Best bet check the gamepass list of regions and mind you not all xgu regions support xcloud and are geo restricted for performance

It's not currently supported, but possible in the future. What games are you looking to play multiplayer via xCloud?