Hey @anuj
Thank you so much for asking the Klaviyo Community for help with your signup form and list!
I have a couple of quick questions for you, Is the signup form from Klaviyo or Shopify? If it is a Klaviyo signup form, do you have it directed to the correct list? Often times the signup form is either a Shopify form which will not add profiles to Klaviyo unless you manually upload the profiles via CSV file or that the Klaviyo sign up form is directed to a different list than intended. From my experience, it is most likely that the newsletter signup form is from Shopify and you will either need to create a Klaviyo signup form or manually upload the profiles.
Hope this helps! Thank you for being part of the Klaviyo Community!