Redwood: Users are unable to raise purchases from Agreement lists / internal catalogs

My customer has a set up of a Procurement BU and then many separate Requisition BU's.

Users are not able to add items to cart or add items to list from internal catalogs which are linked to an agreement. The below errors are experienced:

Error when adding to Cart

LineNumber 1: The item isn't valid. (POR-2011161) Details: The item must be defined in the destination organization with a standard type, a purchasing category, and as purchasable. It can't be an ATO configuration or an outside processing item. LineNumber 1: You must either enter a valid value or an existing value for the CategoryId attribute. The current value is . (POR-2010892) LineNumber 1: The UOM is invalid. (POR-2010266)