I think i have a similar problem.
an account client bought 5 cases beer. I gave him R230 discount and rang it up as an account sale.
after cash-up the cash-up total shorts R460 (double the amount)
but the server amount just above the total on the cash-up slip is correct.
the accounts amount is correct on the cashup slip (R230 less than all account sales)
but the discount was not transferred the the account in back office.