I see this error in your Apache log:
AH01071: Got error 'PHP message: PHP Warning: filemtime(): stat failed for /opt/bitnami/apps/wordpress/htdocs/wp-content/uploads/PDF_EXTENDED_TEMPLATES/tmp/223325. in /opt/bitnami/apps/wordpress/htdocs/wp-content/plugins/gravity-forms-pdf-extended/src/model/Model_PDF.php on line 1049\n',
I don't know if that's the plugin you are using nor if this is the cause of your issue. If you have already set the correct permissions and restarted the server, as I said in my previous message, then I recommend you to check the error with the plugin developers.