Entity kills entity wont change variables anymore

About a year ago, I published my mod. After taking a long break I have returned to work on it, but many things have changed on mcreator. One such thing is that I cannot get my tamed mobs to increase my player-persistent variables anymore. 

Previously I had a mob that when it kills another mob it would gain an experience point, which would be stored in my player-persistant variable. I achieved this by "IF source entity is tamed,  DO variable + 1 of source entities owner. It worked perfectly fine until recent updates. 

Can anyone tell me how to achieve this nowadays?

Update

I figured out a way around this issue, so this has been SOLVED. 

I stopped using the mobs "when entity kills another entity" trigger, and instead created a global trigger. When Entity dies, IF source entity = tamed AND source entity = my custom entity DO increase variable for null get owner of source entity if tamed + 1. 

Hopefully this can help anyone else having this same issue since the update.