I enter reimbursements to members (they aren't actually vendors) as a check and their "acct" shows "past due." I can't figure out why over $5000 has been reimbursed over the years but says $850 is over due, and $250 is open (that might be an unissued check place holding).
The original payment was just by check, so no bill was entered first. We reimburse members that buy supplies, so they aren't true "vendors." I usually just enter a check with the corresponding expense account information and reimburse that way. Making a bill for each member that buys supplies seemed like overkill since some will bring receipts in and we pay that day.
But the report helped me find the past due amounts that arose from writing checks (I can't seem to figure out why some do and some don't end up in "unpaid" because only three out of over a hundred ended up there). I re-entered those ones as bills, then I could clear them.