Problem with a variant and ASIN/GTIN numbers

I have a variant that won’t let me edit it because

‘The value BG*** specified cannot be used as it conflicts with the value BG****for ASIN BG**** in the Amazon catalogue. If this is ASIN BG****, update the value to match the ASIN data. If this is a different product, update identifying information (UPC/European Article Number (EAN)/Part Number/etc.)*

This product uses an GTIN number from UK from my account. It seems to be conflicting with itself and won’t even let me change the product ID even though there’s no other product with that code.

The value ‘004’ specified cannot be used as it conflicts with the value ‘001’ for ASIN Z in the Amazon catalogue. If this is ASIN ‘BG***’, update the value to match the ASIN data. If this is a different product, update identifying information (UPC/EAN/Part Number/etc).*

The product is unique to me so shouldn’t conflict with anything. The tutorial on how to fix is next to useless. Any ideas on how to fix?