I’ve defined Variant meta-field mm-google-shopping.certification, with single line text type
I’ve filled in correct values in that field, in format Google require: EC:EPREL:XXXXX (certificationAuthority, certificationName, certificationCode)
I see that value on certain product in GMC but there is error: Invalid format for sub-attributes [certification] Include a separator symbol between each sub-attribute, and include all required sub-attributes
what happens when you try to use a Google provided value in a spreadsheet. If that also does not work, then either something is not entered correctly, or Google is having issues, but I doubt it’s a Google issue.