Hello -- One of the WordPress sites that I developed and maintain stopped allowing comments to post a couple of weeks ago. (http://www.ghfirebirds.com)
By "allowing comments" I mean the comment form is available, but when a user enters text then posts a comment, it appears to have saved the comment, but the comment doesn't show and isn't listed in the comments area of the WP Dashboard, nor is there any record of it in the database. This is true regardless of whether or not the user is logged in.
Here are my "discussion" settings:
[X] Attempt to notify any blogs linked to from the article
[X] Allow link notifications from other blogs (pingbacks and trackbacks)
[X] Allow people to post comments on new articles
[ ] Comment author must fill out name and e-mail
[ ] Users must be registered and logged in to comment
[ ] Automatically close comments on articles older than days
[X] Enable threaded (nested) comments  levels deep
[ ] Break comments into pages with top level comments per page and the page displayed by default
[ ] Comments should be displayed with the comments at the top of each page
[ ] Anyone posts a comment
[ ] A comment is held for moderation
[ ] An administrator must always approve the comment
[ ] Comment author must have a previously approved comment
Here are the steps I have taken to troubleshoot:
- I have tried disabling all plugins and reverting to the 2012 theme.
- I tried resetting permalinks to the default.
- I have reinstalled a fresh version of WordPress 3.5 via FTP
- I have confirmed that I can not comment on posts that previously allowed comments.
If anyone knows the solution to this problem or has any suggestions of other steps to try, I would be very grateful! THANKS!!