Your item with variants will not appear until you add an Attribute Option.
In the example below, the item shirt was created and given the attribute Size. But because we did not assign the attribute options, there are no variants added to the item. As such, the item will not appear in our inventory with variants.
To fix this, re-create an item and be sure to add options to the specific attribute. For example, Small, Medium, Large options for the attribute Size.