You are attempting to change an identity attribute for this SKU. To proceed, please delete this SKU and recreate the SKU with the appropriate identity attribute. For more information and detailed instructions, see: https://sellercentral.amazon.com/gp/help/23191.
This means that there are product details in SellerChamp that do not match the details that Amazon has on file for this SKU.
Amazon thinks that the SKU is being listed to the wrong ASIN
Amazon is trying to prevent you from possibly updating this ASIN with incorrect data.
Unfortunately, Amazon does not always provide enough context to easily identify the specific information that is causing the issue exception to.
Occasionally, this exception can be due to a UPC conflict (i.e. your product's UPC does not match the product's UPC on Amazon).