The provided link refers to ISSUING a Credit Note - and that work ok thank you.
However, the problem is with RECEIVING a Supplier Credit note.
A support ticket was raised and the answer provided is that this feature is not yet available and to keep an eye on the versions updates (although as we know, no details are provided with updates)!
I will add the feature request to the "developer suggestions" and in the meantime fiddle with the Journal etc.
Great software still.