why prestashop doesn't show correct sku quantity in product list?

PrestaShop often displays incorrect total stock quantities in the product list due to orphaned records in the ps_stock_available table from deleted or recreated product combinations.

This bug persists across versions like 1.7.x to 8.1.x, where deleting/re-adding combinations leaves behind id_product_attribute rows with non-zero quantities that aren't cleaned up

Common Causes

• Combination lifecycle issues: Deleting a combination (e.g., to temporarily hide it) doesn't remove its stock record; re-adding creates a new ID, leaving the old one with stock (like a returned order adding to the ghost entry).​

• Order cancellations: Returns restore stock to the original (now-invalid) combination ID, inflating the product list total without updating visible combinations.​

• No auto-recalculation: Product list pulls a cached or summed total from the database without filtering invalid combos.​

Prevention
Enable advanced stock management or avoid deleting/recreating combinations—instead, set inactive combos to 0 stock and hide them. For bulk fixes, third-party tools like Store Manager can regenerate totals. Update to the latest PrestaShop if possible, though the core issue remains open.
Or set the qty to 0 before deleting the combination.

fix with sql command in database
** Backup the database first **

1/. Get the product id first

SELECT id_product, reference FROM ps_product WHERE reference LIKE '%RC-JST001%';

2/. Get the id_product_attribute

SELECT sa.id_product_attribute, sa.quantity, pc.id_product_attribute as active_combo

FROM ps_stock_available sa

LEFT JOIN ps_product_attribute_combination pac ON sa.id_product_attribute = pac.id_product_attribute

LEFT JOIN ps_product_attribute pa ON pac.id_product_attribute = pa.id_product_attribute

WHERE sa.id_product = [YOUR_PRODUCT_ID] 

  AND sa.id_shop = 1 

  AND sa.id_product_attribute > 0 

  AND pa.id_product_attribute IS NULL;

3/. Delete Orphan product attribute

DELETE FROM ps_stock_available 

WHERE id_product = [YOUR_PRODUCT_ID] 

  AND id_product_attribute = [ORPHAN_ID] 

  AND id_shop = 1;

4/. Recalculate Parent Total

UPDATE ps_stock_available 

SET quantity = (

  SELECT COALESCE(SUM(sa2.quantity), 0) 

  FROM ps_stock_available sa2 

  INNER JOIN ps_product_attribute pa ON sa2.id_product_attribute = pa.id_product_attribute

  WHERE sa2.id_product = [YOUR_PRODUCT_ID] 

    AND sa2.id_product_attribute > 0 

    AND sa2.id_shop = 1

) 

WHERE id_product = [YOUR_PRODUCT_ID] 

  AND id_product_attribute = 0 

  AND id_shop = 1;