Hi: I’m sorry you’re encountering difficulties.
I realize you already indicated that you had tried a number of troubleshooting steps, but I’d like to reiterate and expand upon them a little and see if they help with this:
- Please ensure The Events Calendar and Events Calendar PRO are up-to-date
- Deactivate all other plugins
- If you are using a caching plugin, please follow their instructions on completely disabling it
- Switch to a default, unmodified theme: Twenty Twelve is an excellent choice
- Finally, visit the Permalink Settings admin screen – you need change nothing, though, as just visiting this page refreshes a set of rules stored internally by WordPress
With that done, please confirm if the problem persists. If it solves the problem, reactivate everything one-at-a-time checking every time something is activated to see if the problem has returned.
This is a great way of potentially catching any conflicts.
Let us know how you get on 🙂