Course Completion Certificates after upgrading to Coursepress Pro

Love the feature for auto-generating Course Completion Certificates in Coursepress Pro, but after updating an existing course from standard to pro, I cannot seem to get it to work correctly. I see the link generated in the system beside Units | Notifications | Certificate but when I click "Certificate" I see the following:

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 342410 bytes) in /home/selahthunder/public_html/wp-content/plugins/coursepress/includes/external/tcpdf/tcpdf.php on line 12457