Why is my Klaviyo tracking code not identifying active on-site users?

Klaviyo fails to identify active users when the onsite JavaScript snippet (Klaviyo.js) is missing from your theme header, or when users visit your site without clicking an email or submitting a form.

“Most minor website breaks are caused by simple script conflicts, legacy code blocks, or broken API handshakes. We identify and clear these issues immediately as a straightforward, one-time fix.”
— Jeff Bollettino, Managing Director, Ignite Conversions