This only applies to Flash Sales where you yourself submit the data for the Flash Deal. This will not apply to Flash Sales your category manager (or anyone internal to Shopee) might independently sign up your SKUs for.
After you submit the SKUs and specific quantity for the Shopee Flash Sales, once Shopee approves it, their system will automatically send a message to OneCart.
When that message is received by OneCart, OneCart will:
1. Check if the specific listing & variation combination in the Flash Deal has been matched in OneCart (ie, appears in Listings, not just in Imports).
2. Reduce the available quantity shown in OneCart by the reserved quantity amount.
3. If "auto-update listings" is toggled on, then OneCart will update the new Sellable stock quantity to all linked platforms for that particular SKU.
4. After the flash sale is completed, Shopee will send another message to OneCart noting the end of the Flash Sale. OneCart will then "put back" the stock that was reserved, and thus bring your stock levels back to the official, accurate quantity.
Here's a simple example:
1. SKU ABC123 has 30 pcs in your warehouse. You are selling this item on Shopee, Lazada, and Qoo10 (each platform shows 30 pcs available for sale).
2. You submit ABC123 10 pcs for Flash Deal.
3. When Shopee approves it, Shopee sends a message to OneCart, which reduces your quantity in OneCart to 20 pcs.
4. OneCart updates Lazada & Qoo10 to show 20 pcs available. This is because while you still have 30 physical pieces in your warehouse, you can only sell maximum 20 pcs on Lazada and Qoo10, since 10 pcs are "reserved" for Shopee and the flash sale.
5. When the flash sale starts, you get an order from Shopee for 1pc. OneCart will show 19 pcs left
6. At the same time, you receive an order from Lazada for 1 pc. OneCart will show 18pcs left, and update all platforms to show 18 pcs available for sale.
7. After the Flash Sale ends, OneCart will "put back" the 10 reserved pieces into your inventory. Since the flash sale order was already counted in 5), your final quantity in OneCart will show 28 pcs, which will reflect your actual available stock in your warehouse (since you need to full 1 pc for the Lazada order, and 1 pc for the Shopee order).
Very important ! You should not be manually adjusting inventory when a flash sale is going on. This will result in discrepancies after OneCart puts back the reserved stocks when sales end.
Any overselling is due to incorrectly changing the quantity in OneCart during this process, not due to system error in OneCart.
Don't worry about any negative quantities during Flash Sales. You can always see which SKUs are being reserved for Flash Sales via the "Marketing > Shopee Promotions" section in OneCart.