Hello,
The Page Visit ID issues are probably triggered by the fact that you don’t have a Pinterest Product Catalog.
Please keep in mind that we don’t create a Product Catalog, we just implement the Pinterest Tag. You can upload your products into a Product Catalog using any XML feed that works for Google Merchant. There are various free plugins that can do this, and we also have a paid one on our website.
The Add to Cart issue: did you manually added this event? Our default event will always send the ID.
Checkout: it will fire when a transaction takes place.
