Eternal gear drop in chicago

I've been farming for eternal gears in chicago's windy city, and according to the drop rates it would be around 51ish ap for an avg drop. I've ran this a total of 15 times so far and not even one drop. That's 315AP in total, am I just unlucky? or is the drop guide incorrect, it doesn't seem like the gears drops at all from windy city.

I've now went back to farming gears in London like I used to and it's been dropping for me around an avg of 1 drop per 3-4 runs which is a lot better than windy city considering I ran it 15 times and not even one dropped.