Hi @jiajiajewelry,

Thanks for joining our Community and thanks for the great question! If you receive the error message "Unable to detect that signup forms are successfully installed on your site, but have correctly added the installation snippet to your website (or are using a prebuilt integration that does this automatically). This may appear if you are using a tag management platform (eg. Google Tag Manager) or some other method to deliver the snippet to your website when the page loads.

This message will not prevent you from publishing a form so if the snippet is correctly installed on the website you should be fine to ignore it. So it sounds like what we need to troubleshoot is why the profiles aren’t being added to your list.

Since you are using a custom theme, not a default theme, an additional step needs to be added to your embedded form to ensure that your subscribers are synced to the correct list. You would need to add the following hidden input tag  to your form's input group: 

 <input type="hidden" name="contactmtags]" value="newsletter"> 

Your form’s input group would be in your footer.liquid theme file in your Shopify theme. As this would require editing code and code can be very sensitive to error, I would recommend reaching out to your theme developer or a to a Klaviyo Partner to custom code this for you if you do not feel comfortable. 

Additionally, I’d ensure that you have checked to see if your List is set to Double Opt-In. A user signing up for a newsletter, but not confirming their email again could be another reason why their profile is in your account, but not in the proper List. Let me know if you have other questions and have a great day!

~Chloe