Hello Bex, thanks for commenting on this thread, so if it has a 10% difference that is most likely be why it is not finding the match for you as the way the find match works is it does of the date, account and amount and if any of them three or different it will not bring up the match for you.
It turns out the client created two invoices and the customer paid one amount for both. So QB does not recognize/match the transactions as there is more than 10% difference between invoice value and payment value - good to know!