I have some problems setting up Google Shopping.
I’ve Created a field GTIN on the variant and filled it with a value
In Litium/UI/settings/products/googleshopping I’ve mapped the field to GTIN
This is the most important field in the feed and when you map this and save then Litium is fetching from Google and populating the Field-options with Google Shoppings own categories, the Litium logic is this happens on Save and you must set this before saving.
Seems like Google has changed its logic and this field is now optional but previous when Litium built the connection this field was mandatory and therefor it had to be set, thus Litium logic was built on their approach.