Issue with Field Parameters (Dynamic Parameter) Not Reverting in Power BI Service

Okay, I guess I figured it out myself.

First, to provide a bit of context about what I have and what I want: I have a population table of British Columbia's Health Authorities, and a silcer for that:

I wanted to when selecting one of these, the pie chart automatically switch to show the HA's sub-regions (HSDAs), like this (e.g, choosing Vancouver Coastal):

Before the Field Parameter update in Power BI Service, I could do this by a dynamic field parameter. But as the July 2025 Update explains, now it preserves the hierarchy so by unselecting the slicer you would get all the HSDAs in the pie chart, not the HAs. 

So, what I did:

I created a table like this:

and created a measure to calculate the population:

the measure's main feature is to generate BLANK() when the HSDA is not selected and BLANK for the location scopes that are not within the selected HA.

Let me know what you think.