Unable to display any monitors on restored system

Hi,

I have restored a copy of our site to a new server running ubuntu 18.04 and the latest version of WordPress, MariaDB and PHP 7.2 and everything is running fine other than the Uptime Robot plugin. When I try to change the settings for the plugin the page goes blank and does not reload, also when I view the dashboard I get no content after the Uptime Robot widget unless I remove the API key.

Any ideas? I love this plugin and would purchase a pro version if it was still around!

As this is a dummy restored server I can email you a set of credentials if needed and give access to the db etc ??

P.S. I have tried removing and reinstalling the plugin etc and the page with the shortcode on does not work either, it even looses the WP Toolbar

Cheers, Andy