I have the same Issue:
Info:
I downloaded your free version to see how it would work before joining the club.
I tried looking for this issues under help center articles but could not fine any information.
When I go to create a invoice it goes to a blank white screen. If I click on the order and then the invoice it open the pdf viewer but there is no information in the viewer BLANK.
If I look in the folder wp-contents/upload/ywpi-pdf-invoice/2019 there are no files in this folder.
If I go to woocommerce orders none of the pdf plugin icons are in the right hand column
If I click on the order then I can see the PDF Icons.
After creating a invoice it does show up in woocommerce / orders under the order , but when I click to open it is blank.
I have done the debug like you stated in a another post a few days.
PHP Fatal error: Uncaught DOMPDF_Exception: No block-level parent found. Not good. in /home/xxxxx/public_html/xxxxxxxxx/wp/wp-content/plugins/
yith-woocommerce-pdf-invoice/lib/dompdf/include/inline_positioner.cls.php:37
Stack trace:
#0 /home/xxxxxx/public_html/xxxxxxx.com/wp/wp-content/plugins/yith-woocommerce-pdf-invoice/lib/dompdf/include/frame_decorator.cls.php(700): Inline_Positioner->position()
#1 /home/xxxxxx/public_html/xxxxxxxxx.com/wp/wp-content/plugins/yith-woocommerce-pdf-invoice/lib/dompdf/include/text_frame_reflower.cls.php(330): Frame_Decorator->position()
#2 /home/xxxxxx/public_html/xxxxxxx.com/wp/wp-content/plugins/yith-woocommerce-pdf-invoice/lib/dompdf/include/frame_decorator.cls.php(711): Text_Frame_Reflower->reflow(NULL)
#3 /home/xxxxx/public_html/xxxxxxxx.com/wp/wp-content/plugins/yith-woocommerce-pdf-invoice/lib/dompdf/include/page_frame_reflower.cls.php(123): Frame_Decorator->reflow()
#4 /home/xxxxx/public_html/xxxxxxxx.com/wp/wp-c in /home/xxxxx/public_html/xxxxxxxx.com/wp/wp-content/plugins/yith-woocommerce-pdf-invoice/lib/dompdf/include/inline_positioner.cls.php on line 37
Thanks