[Plugin: WooCommerce Print Invoice & Delivery Note]

The plugin used to work excellently. Now all of a sudden I discover that it only prints blank pages without any content. I already tried reversing everything I did in the meantime, but to no avail.
What I didn’t reverse: I updated to WooCommerce 4.3.1 but I’m not sure if this has anything to do with the problem.
Please, any help is highly appreciated to get this beautiful plugin back running. Any traces I should follow? Things I should check?

Thanks very much!