If you are using a Shopify webshop, and no categories are visible in EffectConnect, then you may have configured the categories in Shopify as 'collections'.
We understand that collections are shown as categories on the frontend of your shop, but when importing data, these collections are not recognized as categories.
If you would like your products to be in the right category in EffectConnect, you can assign your products to 'product types' in Shopify. These will be imported as categories in EffectConnect.
For more info on these product types, please read this article on Shopify's website.