I know its a little late but i'm adding a reply for those who may have stumble upon this question ( like I did).
I also faced the same issue. When I scheduled a pdf delivery, I noticed that of the 2,600 rows, most of it got truncated. I found out the issue is that Splunk has a default pdf report of 1000 rows, which splunk gives you an option to change when you export a report to pdf. However, Splunk does not give you that same option when you schedule a report and set the action to email a pdf. Thus email pdf is defaulted to 1000 rows and you wont be able to change it in the web UI.
To change it in the backend, go to outputs.conf. Increase the max_rows_per_table in the [pdf] stanza. That should fix the issue.
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