In the past, Blogger users have occasionally had to deal with a comment count bug that is usually easy to fix. That bug has returned, the fix no longer works, and there are other bugs that have arrived that are related to comments. If you have a Blogger account and sign in to Blogger before you post a comment, you may find that the comment does not appear until much later, or you may find that it posts right away, but disappears later. If one of those things happens, you can comment without signing into your account--until the Blogger staff fixes these problems. You also may find that you can sign into your account and post comments without any problems at all. Some are affected by these bugs, and some are not.
If you have a Blogger blog that allows comments from people with Blogger accounts only, some of us may not be able to post comments on your blog until these bugs are removed.
For now, if you post a comment and the comment count on the post does not change, don't assume that someone hasn't posted a reply.
The Blogger staff is aware of these problems and is collecting data so that Blogger can be repaired.