Shopify has an order routing system that will assign orders to a location with the expectation you ship from that same warehouse. SKULabs allows you to link your warehouses to Shopify locations.

When you ship an order, SKULabs marks it fulfilled on Shopify at the location Shopify assigned the order to. If you actually shipped from a SKULabs warehouse linked to a different Shopify location, Shopify's per-location stock for those SKUs can be wrong for a while: Shopify counts the sale against the assigned location, not the one the items really left from.

SKULabs pushes stock to each linked Shopify location whenever the quantity it calculates for that location changes, which fixes most of these gaps on the next stock sync.

If SKULabs' number for a location didn't change, it won't push again right away. The Re-push stale stock setting (on by default, in your store's Stock Sync Settings) re-sends unchanged stock every few days to catch this kind of drift. That is not fast enough for high-demand or flash-sale products, so for those you can force a re-push for a single listing right away.

We recommend you reconfigure your order routing within Shopify to assign your online orders to the correct Shopify location that is linked to the warehouse you normally ship from in SKULabs. Contact Shopify support for details.