I don’t know how helpful this is, but it’s the response I got when I sent a request for help yesterday about this issue:

Hi there,

Thanks for writing in.

We turned on a new notification on the post page that is visible to you as the author only. Your readers do not see this alert.

This notification was prematurely launched, and will be turned off shortly.

To be clear, your posts are still publicly viewable on Medium, and we apologize for the confusion.

• If your posts have been curated behind our paywall, or you are part of our Partner Program, your posts are still behind the paywall.
• If you are not in the Partner Program or have not received additional distribution from our curators, your posts are still freely available and visible to all readers. They are not behind our paywall.

In short, nothing changed on the visibility status of your stories.

The new curation and distribution options will be available to all users in the next days, so please bear with us.

Again, we are sorry for any confusion, and if you have any further questions let us know.

Andy
User Services