mpdf.php issue with PHP v7.1.17

Hey there,

First of all, you’ve created an awesome plugin!

We have an issue with this addon after we have migrated to new host. We are currently using PHP v7.1.17 and we have this error:

PHP Warning: A non-numeric value encountered in /home/rocktape/public_html/wp-content/plugins/gravity-forms-pdf-extended/vendor/blueliquiddesigns/mpdf/mpdf.php on line 16874

We already updated to Gravity PDF v4.4.0

Can you please advise? Some of the GF entries returns error 500 when we try to convert into PDF and the error above will be recorded in the log.

Thanks!