Hello Josh,
Posting the Item charges works same on the NAV and the BC.
If I can remember, you have one invoice that is posted without item charges. Afterwards, you wanted to add item charges for one item.
I think that I suggest you create a new Purchase Invoice through which you will post item charges.
In NAV can I still open a Purchase Invoice and insert Item charge line to apply to the PO210001 ?
In the BC, as well as on the NAV, you need to open a new Purchase Invoice (if you completely invoice and ship your Purchase Inovice/Order), add item charges on lines and Get desired document on the Item Charge Assignment for which you want to add item charge.
However, I did try to do a CN against the PO210001 item that was invoiced, but item is still at Qty Invoiced.
Based on this sentence, I don't understand do you wanted to add or remove quantity of the PO210001?
Adding item charge will not affect on any item quantity and entries related to posting of item charge you can see on the Value entries page.
Please Josh, could you explain current issue more, since now I do not understand do you have a problem with item charges or quantity invoiced?
Greetings