There are two reasons why you might not be able to share a given post to Twitter:
- The post content is too long.
- The content is not enabled for Twitter.
1. The post content is too long:
If you edit a post and it is more than 140 characters (not including the URL), that post will no longer be sharable on Twitter, due to the social network's own character limits on posts.
2. The content is not enabled for Twitter.
Some posts may not have been enabled for Twitter by the content creator. In these cases, the Twitter bird icon will not appear at the bottom of the post for you to be able to share it to.