Disappearing posts/topics

[SpacePope]

Hi! We're having some very mysterious bug where topics/posts will seemingly disappear at random after being posted, sometimes hours later. It only affects -some- posts/topics, others being fine, but I've not been able to find any sort of pattern that'd explain it.

No errors appear in the log, and they're not in the recycling bin. We run SMF 2.1.4 and have five mods installed:
- unicode emoji for smf (1.1)
- Ultimate Menu (2.0.2)
- Quick Spoiler (1.5.4)
- Video Embed (1.2)
- HtmlButton (1.0)

Trying to repair errors in the maintenance menu doesn't fix the missing content. Some disappearing threads can still be accessed with a direct address or by using the "Next/Previous Topic" in a board, but won't show on the board itself. Others seem to have been fully removed, links leading nowhere.

Any thoughts?

[Aleksi "Lex" Kilpinen]

This quite simply does not happen without either someone actually removing the topic, or the server doing something really funky (like serving old pages from a cache). Could you check your database to see if the post is still there?
If it is, contact your host and ask if they are running some sort of cache like Varnish that could be serving stale content to your users. If it isn't, check your forum's admin and moderation logs, and your user permissions.

[Doug Heffernan]

Can you check the admin/mod log and see if there was any action pertaining to topic/post deletion logged in there? As mentioned above, there is no way that posts and topics will delete themselves or disappear just like that on their own.

[SpacePope]

Admin/mod log is 100% empty of any such topic/post deletion.

We now also have a message saying `"There are 0 topics and 1 posts awaiting approval in this board. Click here to view them all." on a board, but clicking to view the post in question leads to our moderation center, which is empty, and the post does seem to be in the thread and show without issue.

[Doug Heffernan]

What was the latest change done to the forum prior to this happening?

[SpacePope]

None   

We transferred our forum over to SMF around 2 months ago and everything worked fine, but in the past week these disappearing posts/topics have begun being reported by our users. Past the initial setup we did around 2 months ago, we haven't touched anything forum related other than to post some content. Permissions were edited to add folks to certain membergroups, but nothing in-depth or that'd remove the ability to see a certain post. I'm on an admin account and can't find the missing posts, either.

[Kindred]

It's almost definitely related to a cache issue.

As noted above talk to your host and disable varnish or wharves site caching your server uses.