Today I consider myself a very lucky person, just ran into a Pupitar like 20 mins ago on my way to work, but what makes me mad is that he was just at a stop, not close, not even a meter from it, just on top of it, and the tracker did not show him at all, not when I was walking to it not when he spawned just on my feet, but it showed a sentret and a murkrow that were standing in the same stop (even a bit far from it).
Also my tracker was not even full of mon, it showed 8/9, so I don't think that something else took that Pupitar spot on the tracker because it was showing me mon that were pretty far away (3/4 stops far from me)
Has someone experienced something like this? How can it be that the most rare mon are not showed on the tracker sometimes? I am now wondering how many good catches I have missed just because I did not went to a particular stop when the tracker only shows bad stuff?
NOTE: I know that a minute or two before they actually despawn mon are removed from the tracker, but this is not that case either because I was walking in the same street that time before and with the tracker always opened.