Populating a repeating group with database that is a list of things

I am now looking to filter my results. My setup of nested RG’s is as per the article I linked to (child RG within parent RG) but the following filtering metric doesn’t seem to work (filtering by “current cell’s recos”):


I also tried filtering by “current cell’s index” and that also did not work.

Filtering only seems to work when you filter by this metric (“This number”) however this filtering method doesn’t allow me to filter by what I want to filter by:

For reference, I have my parent RG set up like this:

And the child RG is set up as shown in the first two pictures.

Also, when I say “doesn’t work” when referring to the filtering, the RG renders blank.

I really need some help figuring out how to filter my results in this nested set up. The reason I need this nested RG setup is because it seems that is the only way to display the results of a dataset which is comprised of a list.

Thanks in advance