Often Quicken matches up transactions downloaded from banks (Bank of America, US Bank) with scheduled transactions I've set up in the near future based on AMOUNT, disregarding payee. For instance, I have a scheduled monthly $100.00 manual bill for ABC Co. on the 10th set up in advance, which I've said "I'll pay". On, say the 5th, download transactions from the bank includes a $100.00 (exactly) random payment to XYZ Co. (unscheduled). Quicken matches up that payment to the ABC transaction in advance and does not create a new transaction with XYZ as the payee. Around the 10th the true ABC transaction gets downloaded as a new transaction and confusion reigns if I've not done my reviews diligently. It's fixable but I wish Quicken would pay attention to the payee information from the bank (which it has) as well as the amount before making the match. I can't tell how far Quicken reaches out to find possible amounts to match up to (one month?) but it's at least 5-10 days.
On Quicken Classic for Mac, v 8.2.0