Recently payable account shows a red minus value after a payment? Searched for ever to find why all other transactions are normal.
By total accident discovered that if auto number invoice is used, then its normal.
Adding an invoice number makes a red entry.
The solution, make sure the payables account has the same invoice number for recording and paying, by default it does not add the invoice number on one entry, add it manually and balances show normal then.
Perhaps add a tip somewhere on this in help file or cause gnucash to copy custom invoice numbers on debits and credits so they match payment to invoice.