I get this problem only in one site, upgrading it from 126.96.36.199 to the last 1.6.1
The problem is when the invoice is generated from an order status (the problem is also on the delivery slip pdf).
into the invoice pdf there are many payment method and the pdf has normally 3 pages. First page with a long payment list, the second is void and the last with null data.
The delivery slip is with payment method with no payment method text.
The pdf made from order list and from the order page with the button "View Invoice" has a pdf named invoices.pdf or IN000000.pdf. Instead in the documents list is missing.
Looking into the database, the problems are into three tables:
order_invoice, order_invoice_payment, order_invoice_tax
in the ps_order the invoice number is present, into these three tables is 0 or 1 and all their data is like 1 or 0
I've seen that the data in the other order tables is ok and the order process in the front-office is ok, so it is only in the back-office
CAUSE OF THIS ERROR:
on the new 1.6.1 if the order status are configurated in mode that the invoice pdf is generated after the delivery pdf, the site will get this error and the delivery pdf will report any payment method.
Instead if the invoice is created at the same time or before the delivery slip pdf, all will be ok and the 3 tables of invoice_order will have their data about the order. So the right configuration in on 1111.png
Until to 188.8.131.52 it was without this type of error