Backwards Compatible Xbox 360 Games Not Working

As of a few weeks ago, I tried to load up the original Xbox 360 version of Halo 3 to play it on my Series X before the servers were shut down. I know it's backwards compatible because I've played it on Xbox One X before. I get this error message -

"This Game Is Not Playable Here - Error Code 0x8082000c"

So I tried it with other Xbox 360 games, all the other Xbox 360 Halo titles, the Call of Duty games from Modern Warfare to Ghosts, all games that I know for a fact are backwards compatible, and none of them work. The same error message for all of them. The discs aren't scratched or damaged either.

I got chatting to an Xbox representative who walked me through everything, resetting storage, soft reset of the console, power cycle, resetting persistent storage on the Blu-ray drive, Mac address, etc. literally everything and eventually settled on it being a problem with my Series X as it's a known issue that some of them don't play 360 games and that some Xbox Engineers are looking into the issue.

So, in the meantime, I borrow my friend's Xbox One S to try and play these 360 games, and to my surprise, they don't work on the One S either. I go through literally every trouble shooting step, same as last time and still no difference just the same 0x8082000c error message. Got chatting to another Xbox representative who said it could be due to the store outages but, they only started yesterday. So, why was it effecting my Series X before then?

I honestly have no idea what's happened. Before I traded my One X for the new Series X, 360 games worked and played fine. I just wanna play Halo 3 before it's gone forever, man.

:)