Calculated metric updated post report generation

Hi all!

I'm tinkering with an issue where a previously setup calculated metric is showing variance across reporting days. For instance, todays report says yesterday(6/7) was VALUE, tomorrow the report will be less than what was reported for today, for the same day - (6/7). Add to that, i am seeing the same activity (in reverse, adding metric count) to the same day (6/7) between reports 6 and 7. 

So, calculated metric gains some between reports 1/2, and loses some between reports 6/7 - and report value 7 =/ report value 1. Meaning, the numbers never net back out to their original reporting value. 

What is the cause of this?