Exporting Entries to csv

I am trying to export our entries to a csv file using the button on the entries page. But I get an error that says:-

Server Error
500

The website encountered an error while retrieving https://www.fluxmagazine.com/wp-admin/admin-post.php?action=export_competition_entries&competition_id=28056&paged=1. It may be down for maintenance or configured incorrectly.

This seems to happen no matter which competition I look at. Do you have any advice on how to correct?

Thanks!

Claire

https://www.ads-software.com/plugins/competition-form/