Counts Not Matching: Possible Issue with relationship

I am trying to calculate the count of unique events that took place withing my data.

The issue is, the relationships aren't matching up properly(as you can see in the image with the resulting table and a couple of the measures I tried). For some reason, it isn't matching on the key for all values, and therefore treats them as a wierd hybrid composite key. 

The last image of the "Correct Result Table", is what it should look like. So basically, a group by `TaskId from History`, sum of the Session Count for each. 

I've tried a bunch of different DISTINCTCOUNT, SUMX, COUNT measures, but am overlooking something.

Any help is appreciated, thank you. 

Result Table and Measures RelationshipsCorrect Result

EDIT: 

I made some progress. I managed to calculate the correct value when no slicer filters are applied. I still need to figure out how to make slicers work with this too.