If your store fulfills from more than one Shopify location — a main warehouse and a secondary store, a dropshipping location, a 3PL, a backup site — Nada needs to know which ones count toward "in stock."
The rule
Nada looks at stock across every location that has "Fulfill online orders" checked (Shopify admin → Settings → Locations → open a location).
Stock at those locations is summed.
If the total is zero, Nada treats the product as sold out and will hide or sort it accordingly.
If even one of those locations has stock, the product counts as available.
A worked example
Say you have two locations:
Main warehouse — fulfills online orders ✓ — 0 units of product A
Secondary store — fulfills online orders ✓ — 5 units of product A
Nada sees the combined total (5) and treats product A as in stock. It won't hide it or sort it to the bottom.
If you want the secondary store ignored — for example because that stock is reserved for in-store walk-ins — uncheck "Fulfill online orders" on that location. Nada will then only count the main warehouse, see 0 units, and treat the product as sold out.
A few things worth knowing
Changes to "Fulfill online orders" take effect on the next sort run, not instantly — see How often are the collections sorted? for timing.
The same logic applies to both sorting and hiding. And if a product has multiple variants, the rule applies per variant — a product is fully sold out only when every variant has zero stock at every included location. The full rule is covered in Hiding out-of-stock products.
Common questions
"My product is showing as sold out but I have stock at my warehouse."
Most likely the warehouse location doesn't have "Fulfill online orders" checked. Open Settings → Locations in Shopify admin and confirm.
"I want Nada to look at one specific location only."
Uncheck "Fulfill online orders" on every other location. Nada will then only count the one you want.