You said "Simply go to the app settings, and under identifiers type 'sku'"Please can you send a link or a screen shot of where this "identifiers"setting is on shopify.Kind regards James

Did you get a solution to this?, I have a similar issue I need my mpn to be the same as my sku for my review feed. 

Hi emannauel. I have thousands of products and variants. Do you know if there is a way to auto copy the Sku in to the mpn attribute in shopify? I need to do this as the mpn in my Stamped io review feed is actually my sku. Any help would be much appre...

Thank you for taking the time to reply. I thought you had a resolution from your last post. I have reached out to Shopify as it looks like our settings aren't migrating over to Google.Thank you anyway Yaeli 

We have the same error but I can't seem to see the replies which helped you solve the problem:• Missing value [shipping] in [Shopping_ads] [AT,BE,CH,DE,ES,FR,IT,NL,PL,].We ship actual products all over the world using a third party app Easyship to ca...