We've created an endpoint that has code in place to verify the webhook. That part seems to work well as we received the challenge and echoed it back. The app shows as Enabled and verification was successfufl. However, after that, if I go into my dropbox folder, either online or in the sync'd desktop folders, I don't receive any events.
https://www.clay.run/services/nicoslepicos/dropbox-webhook-handler-start/code
Would appreciate your support, feel free to shoot me an email. In general we're trying to make it easier to work with APIs and Webhooks so happy to give some feedback on our experience too 
Thanks,
Nicolae