Buy Button JS cart not syncing or using main store's cart

[DownUnderDev]

Hi there,

I am using Shopify's Buy Button JS (https://shopify.github.io/buy-button-js/) to create a customized shopping experience and everything is working as expected except when it comes to the state of the Cart.

When adding products to the Cart using the JS Buy Button, the items are not showing up on the store's theme cart. I was hoping they would be in sync, but it seems a new Checkout ID/instance is created instead making the carts out of sync? (Example: 2 items on the BuyButtonJS Cart, but 0 showing on the Cart on the navigation of my test store)

Is this by design or is the Buy Button JS supposed to keep the store's cart in sync? What am I missing?

Thanks