Hi @liamfrench78,
I can see you have plugins installed, so there’s some setting on your system avoiding not related, at first, with flie/folder permission, the most common error.
Unfortunately, server errors can be clueless on frontend side. Please refer to the server logs (Apache, Nginx) to give us extra info about the issue.
On some hosts, you have access to logs through an interface (like cPanel); if you have a dedicated server with console/root access, you can find logs in files like /var/log/nginx/error.log or /var/log/apache/error.log.
When you find your logs, try to install the Expanded Demo; you’ll possibly see entries 500 error or PHP Fatal error like:
./yoursite.com:192.111.111 - - [Jul/27/2017:09:14:18 -0300] "POST /wp-admin/admin-ajax.php?action=ai1wm_export HTTP/1.1" 500 5 "http://yoursite.com/wp-admin/admin.php?page=site-migration-export" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0"
PHP message: PHP Fatal error: ...
Post here your findings so we can assist you.
Thanks