Hi David, I use the premium version of Updraft Plus backup plugin. I recently having similar problem. The hosting is tmdhosting.com and it enables mod_security by default, and I cannot access the setting page of Updraft Plus. They are saying that because the plugin is using phpinfo() and thus conflicted with mod_security.
The remedy is thus disable mod_security, however I don’t think it is a long term remedy. Could you release an update which addressing this issue? I love the plugin and mod_security both. It should work together imho.