Since 10 September 2026 (according to merchants using my apps) , Shopify Admin interface has updated, and the SKU for custom item is not displayed in Admin.
Also there’s a sneaky breaking change by Shopify (I am so tired, can Shopify QA better?) , if the draft order contain custom item with custom SKU , and I add product (or remove product) to the draft order and save, the SKU for all custom items then GETS RESETED TO NIL , and as the SKU is not displayed on Admin, this caused the resulting paid order to omit the custom SKU specified for custom items, which are crucial for order processing.
Please fix this as soon as possible, thank you.