Creation of blocks with agg missing set to off when no data exists

Summary:

Should aggregating data only on missing accounts create blocks when agg missing is set to off?

Content (please ensure you mask any confidential information):

I am writing a rule (in 21.7) where I need to consolidate one dense account member and its children across all dense periods for one sparse year for all other sparse dimensions. We have a moving hierarchy where sparse children periodically move between parents. The parents are stored, and are not dynamically calculated (not how I wanted to design the app but it was required), so parent level data is retained even if children move from that parent.