Fatal error: Uncaught DOMPDF_Exception Ninja Form PDF

Hello when exporting to pdf  I get the following error:

Fatal error: Uncaught DOMPDF_Exception: No block-level parent found. Not good. in /home/domainname.nl/public_html/wp-content/plugins/ninja-forms-pdf-submissions/lib/dompdf/include/inline_positioner.cls.php:37

I’m using Ninja Forms (3.4.20) i.c.w. PDF Form Submission (3.0.4)

A month ago everything worked properly.

What could be wrong and how can I solve the problem.