Same issue here. Reset and Repair did not worked. Editing the registry did not work either.
Same here until Today! The Game Bar showed blank buttons for the previous 9 days. Before that it worked months as intended. Not Reset nor Repair helped and the suggested registry edit was already in place and set to value "1". But today a Win-11 update did the trick. I don't know if the bios-update in it was the cure but they sure make me nervous every time they occur.. Anyways - every Xbox Game Bar issue resolved w the update so I guess thats that. See you guys in the next bug!!! ;)