No categories selected when using shortcode

I have used the [calendar] shortcode on one of the pages on my website, however no events appear once the calendar is loaded because not even the “All” option is selected where the categories appear. I have even tried using [calendar categories="1,2,3,4,5"}.

I have a mini calendar in the side bar of my site and all of the events show fine in that.

This is the page the [calendar] shortcode is on: https://diabetesuknelfsg.org.uk/calendar/

https://www.ads-software.com/extend/plugins/ajax-event-calendar/