There have been over a dozen versions released since v2.1.2. I recommend upgrading to the latest version. Even if the only change on your server was a PHP upgrade, upgrading to the latest version of the plugin will fix any issues related to PHP incompatibility.

When troubleshooting, I recommend clearing your logs directory, then replicate the issue. After the issue has been replicated, immediately check your logs directory for any files that were created.

If you aren't seeing an error related to the plugin or your PHP version, then you may also want to check your browser console for errors. I recommend that you have a developer take a look if you are not familiar with how to debug the browser console.