I raised an invoice for £10 + the 20% VAT I’ve setup so a total outbound invoice of £12. I then raised a credit invoice against this same invoice however its balanced it out at £10 and not taken tax in to account so its still showing a £2 outstanding charge amount which will obviously never be paid as the invoice has been credited.
Seems to be a simple bug in the calculations side of things. Just FYI typically (in my experience at least) you don’t raise -ve value invoices for credits it would just be a normal invoice but flagged as a credit against the associated initial charge invoice and so would cancel some of the balance off.
Images here as it won’t let me attach 3 or add 3 links in being a new user.