We sell Shopify products from our primary website, but we use Shopify for checkout.
From our site, we use Shopify's [myshopifystore.com]/cart/add/[id] URL pattern to allow the person to add the item to their cart and then end up on the Shopify cart page, rather than the Shopify checkout page. (We do this because the checkout page doesn't let them change quantity, add a gift message, etc.)
The problem is that the Google Analytics session gets broken between the [myshopifystore.com]/cart/add/[id] and [myshopifystore.com]/cart/. We know that the conversion linker is passing the _ga parameter via the URL, but it's gone when the user gets redirected to the cart, and the _ga cookie does not match between our site and Shopify's site.
mysite.com (the _ga cookie is 1234) [myshopifystore.com]/cart/add/[id]?_ga=1234 (I can't inspect the GA cookie since the redirect to /cart is instantaneous; but I can see this URL when using Tag Assistant) [myshopifystore.com]/cart/ (the _ga cookie is NOT 1234)
This seems to be a glitch in Shopify, so I don't think there's anything I can do about it. But I'd love any suggestions.
BTW, when we use the Buy Button link (or maybe it's called a checkout link), everything works as expected. The cookies match. But we can't use that for the reasons I mentioned above.