I went digging around on the boards and apparently the last time it was released, all of the Kindreds had different jungle monsters to farm to get stacks. However, when I played OFA with Kindred today, there was only one monster marked for all the Kindreds. So as the jungler, I went to go kill that specific monster but it didn't give me a single stack. This is to say that all of the Kindreds had the same mark on the same monster, yet I was unable to trigger it. This happened multiple times on different monsters, as right after I killed the target monster, the mark would disappear but not give me a stack. It would then reappear on another monster and thus the cycle repeats.
Hopefully Riot will look into this, as Kindred loses a lot of power this way (although I personally think that OFA Kindred is already bad in the first place).