I'm using inline entity form for commerce products (single value form). If I want to do some views bulk operations on the node display I get this error message "This SKU is already in use and must be unique. Please supply another value.".

If I use another field widget everything works fine.

Comments

If you click on the All Product Variations tab (from the products list view) do you see a product without any values in it?

If so it might be the same issue I'm having: https://drupal.org/node/2113847