XBOX Rewards achievement challenge not working

Achievements don’t unlock instantly when you complete them

In some instances, you may meet the requirements to unlock an achievement but not immediately receive a notice or update to your gamerscore. The Xbox Live service validates the unlocking of achievements and, though rare, delays can occur. Don’t worry – your
progress has been recorded and the achievement will be awarded shortly, usually in less than 24 hours.

Achievements and challenges not unlocking while offline

For achievements and challenges to get unlocked and for rewards to be issued, you must have an active connection to Xbox Live. Though you may be able to meet the requirements for an achievement or challenge while offline, you will not receive related notices
or rewards until you connect to Xbox Live.

A challenge disappeared before you could finish it

Challenges are time-limited, sometimes to weeks or months, sometimes to just hours. If you don’t complete a challenge within the time window it’s available, you will not receive a reward.

No gamerscore earned from app achievements

You can earn app achievements for basic use of an app (such as, watching a movie on Netflix), at the app developer’s discretion. App achievements do not affect gamerscore, though they may bring other in-app rewards.

Hadn’t been working for me either, since 8/11/22 or 8/12/22. Going to lose my weekly streak if not fixed by next Monday.

You can check that https://support.xbox.com/en-US/games/troubleshooting/troubleshoot-achievements-challenges

Problems with Xbox One achievements and challenges

After you complete achievements and challenges on your Xbox One, you can claim rewards and raise your gamerscore. To successfully unlock achievements and challenges, you need to make sure the following are true:

• You have completed all of the required elements to unlock the achievement.
  
  Note You may have to unlock a combination of achievements.
• Your console must be connected to Xbox Live. To complete challenges and unlock achievements, your Xbox One console cannot be set to offline.

Challenges must be completed within a set amount of time. You have weeks, months, or just hours to complete the challenge. If you don't complete it within the given timeframe, you won't receive a reward.

You can earn app achievements just for using an app. For example, you can earn achievements by watching a movie on Netflix. These achievements are at the app developer's discretion. App achievements do not affect gamerscore, though they may bring other in-app
rewards.

Completed achievements that are pending confirmation on Xbox Live will be listed as "Done! Unlocking." This means the achievement will be processed in the order it was sent to the Xbox Live service and may take some time to be confirmed.

If you meet the requirements to complete the achievement or challenge, but you don't see the “toast” icon or the achievement isn't listed, try the solutions below.

Because it's not an achievement. It's a banner reward.

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Challenges > Halloween Challenge > Press X > Job done.

Now, however, it seems we may have a better explanation. According to a Microsoft help page, Xbox One achievements don’t unlock while you’re playing offline.

“For achievements and challenges to get unlocked and for rewards to be issued, you must have an active connection to Xbox Live,” explains the post.

“Though you may be able to meet the requirements for an achievement or challenge while offline, you will not receive related notices or rewards until you connect to Xbox Live.”