I have a funny one and I can’t seem to figure out where the issue is happening. I have been placing test orders on Shopify, and Klaviyo used to successfully pick them up as an email subscriber with a double opt-in email request coming through off the back of the order confirmation. However I tried to change the email opt in for that list to single opt in, and now my email marketing is not coming through at all. 

I have a live flow for a welcome series with discount code which I expected for the first email in that series to come through as soon as someone places an order, but nothing happens. 

I have tried and checked the following things:

• The Newsletter list does not show the email subscriber at all when I place an order, so it’s not pulling them into that list. The two systems do talk to each other however as I can see on Klaviyo that it registered someone completed checkout, but the subscriber does not come through to the list 
• In the integrations settings I have checked it is syncing to the right list (Newsletter). I did try change it to the other list momentarily when it was doing the double opt in for Newsletter, which worked with a double opt in as well. However it is definitely pointing to the right place right now. 
• I have checked my flow says to subscribe to the right list (Newsletter) and that the correct emails are shown as live in that flow. 
• I have also given it a few days between sending to see if the issue was with some kind of spam setting where it didn’t send over x amount of emails. I stopped sending on Friday and just tried again today (Monday) with no luck. I have also changed some of the settings in the list to ignore order confirmation emails for purposes of smart sending. 
• I did manually delete the previous 2 personal emails I was using for testing from the Newsletter list, so I was thinking maybe it would refuse to pick them up from the manual deletion, but I had a Google and apparently that’s not a thing. I can give it another go with an email I haven’t deleted from the list if that makes a difference

Sorry for the long post, I have been trying to logically work through where the issue is happening for almost a week now with no luck. Hoping someone here can give me tips on what to try next or where to look!