I can’t post on any social media websites using the Facebook plugin. I type my comment and click comment, but it doesn't post. I created another Facebook account thinking something was wrong with my account, but I still have the same problem. I can post comments with the new account, but once I log out the comment disappears. I'm the only person who can see my comments using my new account. Any reason why my comments aren't posting on social media websites using Facebook plugin? Why aren't my comments seen by others using my new account? Why do they disappear when I log out? Do I have a setting wrong?
Either the account you are using is somehow being blacklisted from commenting with the plugin or there is a bug.
Go to https://developers.facebook.com/docs/plugins/comments and try there.
Also you can test it by placing another URL in the box
If you think everything is in order and it is still giving problems, you will need to file a bug at https://developers.facebook.com/bugs
Here is a list of current bugs with social plugins https://developers.facebook.com/bugs/custom/?tag_ids=127928707302082