Hi Toby,
A few things that may help:
If NewPolicyDoc is never populated, it's likely that the export configuration/template isn't being retrieved correctly or no data is being passed into the export action.
Kindly mark this as the accepted answer if it helps.
I had these roles applied to the app users already but it didn't fix it, I created some more Entity access permissions for the entities that only had Configurator and created access rules for the Exported_ParentXPath and the security is now happy, I'm not sure why this was needed?
I checked the defaults from the module in the marketplace only the Exported_ParentXPath was needed to make it work