I found an old thread Inventory Qty by Location here: https://jetsupport.jetreports.com/hc/en-us/community/posts/115007150967-Inventory-Qty-by-Location. Below is the response.
You should be able to use the flowfilters on the Item table to filter by the location.
Presuming B2 has your NL on the Item table, you could use an NF in C2. For example, if you're after Sales Qty, try something line:=NF(B2,"Sales (Qty.)","Location Filter","<your location code>","Date Filter","01/01/08..12/31/08")
This is off the top of my head, so you might need to play with it a little. You should be able to get the general idea.
My question is this. Why wouldn't you put the suggested Location Filter stuff in your primary NL so that all of your filtering is done there instead of in the NF?