Not receiving webhook notifications

I successfully created a webhook subscription to /restapi/v1.0/account/~/telephony/sessions. The subscription is active and not blacklisted, but my server isn't receiving notifications from that subscription. These notifications have worked in the past, but after deleting my old subscriptions and creating a new one, the subscriptions aren't coming in according to my Nginx logs. My app client ID is 8838LLxeS6aFN-iuh18BmQ and the subscription ID is 16aa1bc3-b3ad-45dd-bd57-f31106006a27.