If I remember correctly, the problem wasn't that it didn't see the move, the problem was that in response to the move it played a few really bad exchanges, like

If I remember correctly, the problem wasn't that it didn't see the move, the problem was that in response to the move it played a few really bad exchanges, like the stupid-looking wedge in the bottom-left, and adding stones to a dead group on the right. Playing bad exchanges when behind is a bad idea even from AlphaGo's perspective. It's still not correct to call it a bug, though.