Size variations should be created for this product. Please add sizes in the "Product Pricing" tab and remove other SKUs created for the same product with different sizes.
This product should have size variations (e.g. small, medium, large).
Products under the following categories should have size variations:
-Sports (Sportswear and shoes)
-Home and Living (Bed Linens)
Proceed to step 4 and click the sizes you have in stock from the SKU Attributes list in order to create variations.