Hi @jarkins,
Thanks for sharing your question with us! Welcome to the Community!
If you have tested and confirmed that users who are consenting to be added to your designated list and/or receiving marketing material yet aren’t consented to receive email, and it isn’t a Double Opt-in issue where users aren’t being added because they haven’t confirmed their subscription a second time, I would check to ensure that you have enabled consent at checkout in Magento 2, following the steps in this guide.
If you have, and can also confirm that you have a webhook secret in Magento, under your Klaviyo configuration, then this might be an extension issue. Can you confirm that you are using and have updated to the latest extension version for Magento?
Thanks for participating in the Community!
-Taylor