Thanks for clarifying, I think I understand your problem better now. You have a Saved Search (from the Discover application) which you are rendering in a Dashboard, and you want to generate a report with all of that data in a PDF, is that right?
Our documentation on this for 7.8 is a bit more sparse, but in 7.9 onward the documentation states:
NOTE: When you export a data table or saved search from a dashboard report, the PDF includes only the visible data.
This is a limitation in Kibana's Reporting feature right now. There is an enhancement request open for this already:
The issue description is focused on data tables and CSV reports, but in the discussion in the comments, users have asked for support for saved searches and PDF reports as well.
You can subscribe to that issue to get updates on progress. It seems like something that lots of people have asked for, and we were unable to implement due to technical limitations until a related issue was completed a few weeks ago.