A Trip Report generates a .zip file instead of a PDF file in Vault.
One or more fields that are requested in the Formatted Output template within the Trip Report are hidden from the user that is requesting the Trip Report. This is due to the Field Level Security on the affected fields.
When there are attachments to the object record that the Formatted Output is generated against, Vault archives the Formatted Output result PDF file into a .zip file that contains all attachments to the object record.
If one or more of the fields being requested in the template are hidden from the user that is requesting this Trip Report due to their lifecycle state-based role permissions, Vault generates a .zip file containing the template and a text file indicating that those fields are hidden to the affected user.
The solution is to allow the affected user to access the affected fields within their configuration.