This how-to is for users of The Events Calendar Pro plugin only. 

There are isolated reports of this happening for some customers and we haven't figured out why yet.

If you experience this problem, the workaround is simply:

  1. On the Edit Event screen, click the Update button
  2. Wait for page to refresh
  3. Click the Update button again
  4. Wait for page to refresh
  5. View the Calendar page

We are searching for a permanent solution.