what else do I need to verify? I have searched but I can't find the solution to this, has anyone solved this?
Hi Mario. Any chance your endpoint is not returning a 200 status response? I found the webhook receiving multiple messages when debugging and thus delaying the 200 response.
Also, if you already managed to subscribe a WABA to your app webhook, can you take a look at https://developers.facebook.com/community/threads/1143645680292731/? and if you can't answe, upvote please.