SM Service Portal - error when checking out more than one item

SM Service Portal throws generic error message when users try to check out more than one item - if one or more of them require Approval. The items can be checked out on-by-one by the user, so the needed priveliges are in place.

If two or more items with no Approval are checked out, the order fails. The items can be checked out one-by-one.

Items are set up with connector to create request. Cart is enabled.