GoKawiilXbox's technology chief said an "unacceptable" outage on Monday should not have stopped people from playing their games on physical discs.
"We're looking into reports that some players were unable to access games using discs as expected during the service interruption," Scott Van Vliet said in a statement.
He said the outage, which lasted around 20 hours, was caused by a licensing issue failing to correctly check if a user was allowed to play a game.
It has poured further fuel onto the fire of fears about gaming's potentially digital future - after Xbox rival PlayStation faced an outage of its own on Friday.
"Disc-based entitlement checks should not prevent players from accessing their games and this is by design," Van Vliet said, originally reported by The Verge, external.
He said a fix to stop this happening again will be rolled out in an upcoming update.
"I think this highlights how important it is to move towards truly consumers owning their digital games," said one commenter responding to Van Vliet's initial post, external.
"If consoles are going to become digital only, then issues like today cannot lock people out of their stuff."