GTINs are barcodes (also called EAN, UPC, ISBN) that are used by Google Shopping to identify products. But its a major issue that google doesn't recognize it and shows Limited Performance Due To Missing Value [GTIN] in the google merchant center even though you have entered UPC codes in your products. After installation just start the process in our app and it will sync barcodes for you. You must have valid UPC codes entered in your product for this app to make it work on google merchant center

Easy Fix Limited performance due to missing value [gtin] on GMC for all productsSkip manual work and start process to sync all the products that have barcodesNever experience GTIN missing when it comes to inventory sync with googleYou must have valid UPC codes in your products for this app to work.