Auctions API broken?

Hello, I’ve noticed this after I switched to new API, but there are a lot of auctions that have 0 buyout value, for example “Greater Flask of the Undertow” (ConnectedRealmID 535 EU):

"Id": 1577151100,
"Item": {
"Id": 168654,
"Context": 0,
"bonus_lists": null
"Buyout": 0,
"Quantity": 36,
"time_left": "VERY_LONG"

Ok, i’ve double checked and it seems now that auctions with quantity 1 have “Buyout” field and the ones with more than 1 item have “unit_price”. Seems very confusing…