I had trouble with an "unknown user" posting in my stories after blocking me. It was only when I got to read what they wrote and who they were in e-mail notifications that I discovered it was spam, not some coward unwilling to face rebuttal.

If the spammer that posted to your story blocked you in a similar fashion it could be that it wasn't the true owner of the account doing so. That doesn't make the account any more visible to you until the owner, Jessica, can be notified of the issue and unblock you. Hopefully, this post will be brought to her attention and that can happen.