AP Invoice Combined for Misc Invoices

Hi all

I am on the latest Epicor Cloud version of 2023.2.11 and have been trying to use the AP Invoice Combined DMT template just for Misc AP Invoices.

I am getting a very unhelpful message saying Index was outside the bounds of array.

There is no clue as to what field it is complaining about.

Anyone got any ideas?
Thanks
Sarah