Hi Jason,
If you go to your Authors page in your backend, you will see this message:
Only authors who has write permissions will be listed here. If your author is not listed here, ensure that they have permissions to write new blog post under the ACL section.

I checked your ACL setting for 'Registered' and it seems they do not have 'Allowed To Write New Post' permission. If you enable this ACL setting for the user group, you can see the users in the Author page in backend and Bloggers page in frontend. Hope this helps.