How did you set the document template? Can you further explain this?
I have the problem with index.tpl
{extends file="parent:documents/index.tpl"}
{block name='document_index_body'}
Test
{/block}
This doesnt take affect the preview and the generated document at all.
Here is another one with the same problem, that not had been solved. https://forum.shopware.com/discussion/33496/extending-bare-themes-pdf-template-for-invoice
Did it as described in the documentation: https://developers.shopware.com/designers-guide/edit-newsletter-and-document-templates/#edit-document-templates
Please help me.