If you find an item does not publish to Ecommerce, currently the most common cause is that the item is impacted by a Lightspeed bug that prevents the item from being sent reliably via the API.
Other causes include the following:
- Item is not tagged "webstore"
- Items is part of a Matrix and the Matrix is not tagged "webstore"
- Item is part of a Matrix but the product in Shopify has a different setup of options (size, color, etc)
Resaving items and matrices impacted by these issues should push them through.