For site moderators
See our Why are comments visible in the Disqus admin but not on my site? documentation.
For commenters
Comments marked as spam
Comments are removed from public view (or "disappear") when they are filtered as spam, whether manually by a site moderator or automatically by our system.
The following commenting behavior can cause comments to be marked automatically as spam:
Including a signature in multiple comments. For example, appending a name or website link to the end of multiple comments. We recommend entering that information at Edit Profile > Profile tab instead.
Bad or strange syntax. For example, excessive paragraph breaks, bad punctuation, double-spaced comments.
Posting the same comment multiple times to the same page, or across sites;
Using multiple links in one or multiple comments.
To prevent this from happening further, contact the moderator(s) of the site(s) in question where your comments are disappearing. They'll want to first edit your comments to remove the relevant text and then approve your comments. If you've posted duplicate versions of the disappearing comment, we'd recommend the moderator(s) approve only one of the duplicate comments and delete the rest in order to keep those comments from being counted against you.
Other non-spam issues
Your comment is awaiting moderator approval
Please see Who deleted or removed my comment? for more information.
Your comment has been removed by the site moderator
Please see Who deleted or removed my comment? for more information.
Sort order not set to "Newest"
Comments may seem to disappear if the comment thread has many comments and the sort order is set to something other than "Newest". Set sort order to "Newest" when posting a comment to keep your comment at the top of the comment thread, at least until further comments are made. Please see Sorting Comments for more information.