I'm working with a new installation of 2.3.5.
I am unable to import a multi-select product attribute.
My attribute I'm trying to import is "Year" for auto parts.
I have tried importing with the column header "year", which is the attribute code. I have also tried importing with the column header "additional_attributes" with value "Year=1967|1968". Neither of these work.
When I manually set the "year" attribute on a product and export that product, it is exported via "additional_attributes" with value "Year=1967|1968".
I've tried importing exactly what is exported, but that doesn't work either. It doesn't give me any errors when importing, it just doesn't change any value on the product.
I've tried using a semicolon, a comma, etc. as field separator. I have "Fields enclosure" unchecked as well.
All attribute values I'm importing already exist within the "Year" attribute.
Any help would be greatly appreciated.