Add Site Category in an Item via CSV Import> Error: Invalid category reference key Information for website <NULL>.

In the User Interface, before a user could select a Site Category for the Item, a Site should be chosen first.

As this is the case, the Site should be included in the CSV file and have it mapped as well during the import or assign a default value by clicking the Pencil Icon and choose the corresponding Site to get away with the "Invalid category reference key Information for website <NULL>" error.