Issue Writing Off AR invoices with tax area code other than "V"

Hi

I have recently encountered an issue when writing off AR invoices whose tax area code is NOT "V".  When a user needs to write off an AR invoice, they add a receipt and after selecting the invoice to write off, they change the TI on the grid from 10 to 15 which assigns a write off amount (as below).  When the receipts batch is posted, there are only 2 entries - 1 to the write off account and the other to the AR control account, even though the original invoice has VAT.  I believe this is because the tax area code is C and not V.  If the same process is done with an AR invoice with a