While investigating I did a quick online search and found this post from Mohammad R. Daoud, one of the Microsoft Dynamics GP MVPs which references the same error message.
As he explains the problem is down to the enhancements Microsoft have made to the cheque remittance process. In doing so the PM_Payment_WORK table has been replaced with pmRemittanceTemp. The hard way of fixing this is to revert the modified report to the original and recustomise. However, if you export the package, edit in a text editor and replace instances of PM_Payment_WORK with pmRemittanceTemp, change the Key from 7 to 3 and then import the package.
So having done this I then tried to generate the remittances again and got the following error message;
Mohammad also warns that you may need to replace some of the fields you have used from PM_Payment_WORK if they are not on pmRemittanceTemp. I couldn't see any fields that we were using that were not on pmRemittanceTemp so dug a little deeper. It seems Microsoft have removed the ability to link any of the payment run tables to the PM Creditor Master File; we were linking to this table in order to display the creditor address at the top of the remittance, where it would show through the window on the envelope.
Now while there is a workaround to this error, VB script and the Global Function RW_PMAddrIDInfo, this is going to be a lot of additional work as every single one of our customers has a remittance set up in this way. This is not going to be an enjoyable task.