When playing an Xbox 360 game through my Series X, why aren't achievements carried across?

Thats weird. I wonder if it takes extra time. The 360 is old, but by technology standards, its almost prehistoric at this point. Especially from a networking standpoint. I would sign out and back in and see if it updates.

Achievements unlocked while playing on a series S/X aren't separate,they're just the same as xbox one achievements.

It's not like the xbox 360 & xbox one where the achievement system was made slightly different,the xbox one & series consoles use the same achievement system.

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.

I’m having the exact same problem on my series x and on my Xbox one

Hello there,

every Xbox 360 and or Xbox one game you can play via backwards compatibility on your series X/S share the same multiplayer network, so yes you can play those games with your friends across different generations of Xbox. However for future games releasing
on Xbox one and series X/S separately, I can't confirm that it will work a 100%.

It was so weird, there was no issue with the achievements popping when I started playing it on my series s but when I finished Easter island there was no achievement but assumed it'll pop later so got through new york mission and no achievement again? So I stopped playing! Recently dusted off my 360 and downloaded red alert to see if I can go through the game and get the missing achievements but it appears that the gaming gods have forsaken me!