Failed to open stream error, referencing disallowed FLOCK() function.

Hi, I am getting hundreds of errors in my log every day that look like this:

PHP Warning: _wpe_old_file_put_contents(/path-to/wp-content/uploads/dompdf-fonts//dompdf_font_family_cache.php): failed to open stream: Permission denied in /path-to/php_prevent_flock.php on line 58, referer: MY-WEBSITE.com/my-account/current-month/gyms/

The above referer path is a page that my members often export to PDF using the WP PDF Templates plugin (i.e. /my-account/current-month/gyms/?pdf). I contacted my server administrators (WP Engine) and they informed me that the FLOCK() php function is disallowed on their servers, which is why this error is being produced. The problem I’m having is that I cannot find where the FLOCK() function is being used in the WP PDF Templates plugin.

Can you tell me where to find this in the code please?

Also, as I mentioned in another support thread, as you can see in the above error, the requested path to the dompdf_font_family_cache.php file is incorrect, with two forward slashes after the font directory, i.e.: uploads//dompdf-fonts/.... This is due to the incorrectly “redefined” font directory in wp-pdf-templates.php on lines 95 thru 102.

Please let me know where the FLOCK() function is being called so I can attempt to stop this error from filling my logs every day.

Thank you so much for your assistance.