Is not being possible to change the sku of an order because the OMS uses the search API (which is related to the catalog V1) and seller portal accounts use a new catalog version. No proxy was implemented on this area.

The error is: "A conta solicitada {accountName} não foi encontrada no banco de conexão." <> "The requested account {accountName} was not found in the connection bank."

1. Go to OMS and select the order you would like to replace the sku (it has to be a seller portal account);
2. Check that an error appears on the UI;
3. Inspecting the error is possible to see that the message is the one above.

No workaround.