Wentworth's item price history shows recent sale for less than my buy order

[popter]

I've had a buy order for 500k for an IO for a few days. I checked today to see what the price was like, and there's an entry showing a sale for 20k from today.

I thought the person with the highest buy order greater than than the list price should get the item when someone makes a listing, but clearly this didn't happen. (Or there's a display bug that would likely impact market prices).

 

Here's a screenshot: