Hi there @Poetype,
Welcome to the Community! Happy to help!
Products not populating in your edit mode in your email template is expected behavior! This is why you see the products successfully populate in gmail. However, outlook is another story.
Unfortunately, Outlook is one of the trickiest providers to work with for various reasons, we have provided further documentation in our Help Center: Why Does my Email Look Different In Outlook. Basically, from Outlook 2007 onwards, Microsoft stopped using Internet Explorer to render emails and instead opted to use Microsoft Word as its rendering engine. This is awful for email marketers and developers who use HTML. Try copying and pasting an HTML web page into a Word document and you’ll get a glimpse as to how Word translates HTML. There is not much control Klaviyo has over how Outlook renders images/styles.
I’d recommend taking a look at a similar issue to gain more insight into this!
Thanks for participating in the Community!
-Taylor