Events not filtering by category

We are using this shortcode:

[events orderby=”event_start_date” categories=”exeter” show_filters=”false”]

Until recently this was only showing us events in the category ‘exeter’ which is what we wanted. Today I checked and all events are showing. We have not made any changes to the page or shortcode. This is happening across the site not just on this page.

The page I need help with: [log in to see the link]