Hi @Cr.oompp,
Thanks for sharing your question with us, happy to help!
Unfortunately, Klaviyo does not collect SMS consent via Facebook Lead Ads at this time, which is why the consent didn't come through. However, I will submit this as a product feature request on your behalf.
In the mean time, in order to add consent to the Profiles you currently have in Klaviyo that came from the Facebook Lead Ad, you will need to re-upload the contacts via a CSV file with their number and country. Later on you will be asked to click a specific button that says ‘Update SMS consent’ upon upload. This will add the SMS consent to the existing Profiles in Klaviyo and then you can start sending SMS campaigns to those who opted-in via Facebook
In order to start collecting consent in Klaviyo via Facebook, you will need to pass it to Klaviyo via a CSV file or our List API.
You can also collect consent via Instagram by following these steps.
Thanks for participating in the Community!
-Taylor