Activity feed items keep reappearing

What items are you taking about? Are these your items or others activities. It's possible for others to reshare achievements.

Activity feeds on the Community tab, player profiles, Clubs, and game hubs allow players to see and comment on what others are playing. These feeds also display game clips and screenshots, known as captures.
To report an inappropriate feed item or comment:

1. Select the inappropriate activity feed item or comment.
2. Navigate to the offending player's Gamertag and select Options, and then select Report.
3. Select Inappropriate feed item or Inappropriate comment, depending on what you're reporting.
4. Select Add comment to provide more information. When finished, select Report.

Club feed items can be reported to either a Club admin or to Xbox. If the item doesn’t belong in the Club, select Club admin. If the item violates the Code of Conduct, select Xbox Live Policy
& Enforcement Team.

You can also remove your own activity feed items and any comments associated with your content. To remove a specific feed item or comment, select Options, and then select Delete item or Delete
comment.

Having things disappear from your activity feed, even on your own profile, is a fairly common issue for quite a few people recently. My pinned post on my profile always disappears and reappears. Just give it some time, and it will appear again. I saw someone
posting on my feed the other day that the most recent post they could see was from 1 year ago, and they are active daily on Xbox. So it's a big issue for some right now, sorry to say. It should reappear after a while, hopefully within a couple of days.

Hi there,

not sure you can share the club info itself, but you might be able to create a activity feed item within the club and share (and pin) that on your own activity feed itself.

Could you see items from your friends in your activity feed ?