I subscribed to the messsages webhook, and it works perfectly with the numbers owned by my account. If I text one of those numbers, I get the webhook notification

However, whenever I text one of my client’s phone numbers (managed by my account, and onboarded with the embeded sign-up flow) I get nothing at all…

If a separate webhook subscription is requiered for managed phones, I have not found where to do it anywhere in the meta for developers site! Is a separate webhook subscription required for managed phone numbers?