Adding an Invoice to the AIF Queue Manager

Hello,

I have a query regarding how documents get added to the AIF Queue Manager.

When I use SalesSalesInvoiceService.read as an Endpoint Action Policy and print an invoice to file, it gets added to the AIF queue manager – This is correct behaviour I believe?
When I use SalesSalesEInvoiceService.read as an Endpoint Action Policy and print an invoice to file, it actually prints it as a text file and doesn’t add it to the AIF queue manager, even though all the other settings are the same as above.
I’ve enabled it as an Action and the Action Type is a ServiceOperation, so that seems right to me. Is there anything I’m missing here as I’d prefer to use the Schema for the EInvoiceService?