Hi @Nachin
When a visitor comes to your site, Klaviyo places a temporary cookie. However, it won't start tracking activity (if enabled), including product viewed, for that visitor until they are identified by their email. They then receive a semi-permanent cookie that lasts for 2-years.
That identification occurs when the visitor either submits a form, starts checkout, or clicks a link in an email you've sent them. That's why often you'll see a contact's event timeline that has a checkout started event with no viewed product event beforehand i.e they weren't cookied until checkout so the product viewed event isn’t captured first.
If you have profiles in your newsletter then they should be cookied but that depends on how those were added. If imported, then Klaviyo won’t know that a visitor to your site is tied to one of those emails until form submit, checkout, or email click.
The easiest way to test viewed product events are being captured ok is to navigate to your website url using [yourdomain]?utm_email=[your test email], which will create a profile and cookie you. Just add your website domain and test email address in those placeholders. Then view a product. Then see if a viewed product event has been captured in the product viewed activity feed.
If you do not see that test event in the product viewed activity feed, there is an issue unrelated to the above.
Let me know how you get on.
Andy