Cannot Access Setting Page

Have this plugin working great on two other sites. Just installed it on a third site and click on Settings — the page loads, but there is nothing below “Viewing Events”, “Adding/Editing Events”, or “Advanced”. Clicking on the “If the form below is not working please follow this link.” does nothing.

All three sites have the identical theme, identical plugins loaded and activated. Any thoughts?

https://www.ads-software.com/plugins/all-in-one-event-calendar/