I have done as mentioned in https://world.episerver.com/forum/developer-forum/Episerver-Commerce/Thread-Container/2017/12/inventory-not-reduced-11-4-1/. However, it's not working.
Do you setting in the inventory tab in Catalog UI like this:
In Quicksilver, after I setting like this for "Puma Roma Turbo Mens" code is SKU-39850363 for all stores with Quantity = 6. I placed an order for this item with quantity is 3 then the inventory updated the in stock to 3 for my default store (Stockholm).
This is the order placed: