Our guild tried 2 bounties tonight (Desolation EU, around 10CET), both times we got Yanonka and had probably a dozen or so people scouting for rats. Not only were we unable to spawn Yanonka, nobody could even find a single rat with the full 15 minutes. Both times. Many of us had seen them around prior to tonight and were looking based on known locations so we knew generally where and what to look for.