@Paul from Concise Digital 

Well first 10 days attribution to Klaviyo is a lot, i would suggest keeping it to 5 which is the basic setup.

And second thing is the way of attribution. I assume shopify uses url tracking while Klaviyo does cookies tracking. The difference is I assume that shopfy will show you as Klaviyo revenue only if someone directly clicks on the email, goes to the website with utm codes from klaviyo and buy in that specific visit, while Klaviyo because of the cookies has better way of tracking people so even if they open your email on one device and decide to buy in another (if they were cookied on both devices before) it will still be able to be counted as Klaviyo attribution. So for Klaviyo attribution only 2 things need to be happening for it to be added as Klaviyo attribution and those are person needs to buy in the 5 (in this case 10) days from the moment of sending the email, but before buying they first need to Open or Click an email. 

So in a way Klaviyo is tracking actions while shopify is probably just following the URL utm codes..