User might encounter missing SKU in OMS, below are two things to troubleshoots the situation.
1. Check if the specific order from Sales Channel platform, is there a partial refund happening. For the cancel/refund of
partial products, it will not be sync into OMS.
2. Is the product are KIT/Bundle setup recently, should the KIT component item are added right after the order are confirmed/sync to OMS, the KIT component item will not be added. The new KIT component item will take effect on the next new order.
Should the above two scenario is not applicable with your situation, kindly raise ticket with help@selluseller.com for our technical team to further investigate.
Anchanto Support