There is a specific configuration - invoices or some other financial documents are sent only to specific customers (there is a condition in the notification template). The notification is not sent (as expected), but as a result attempt to download the same PDF-document from PCP is not successful - empty PDF is getting downloaded. If we click on "Rebuild PDF", the correct PDF can be downloaded.
The issue is caused by the bug with id #PBA-80362 ("Empty PDF document is downloaded").
Please contact PTA team/TAM to clarify the status of the bug.