Hello,
Does anybody know why dropbox webhooks work only after I click Generate access token button ?

I have configured a webhook which is successfully verified by Dropbox. I have files.metadata.read permissions checked. However when I create new folder or upload a file in my Dropbox account the webhook is not working if I don't explicitly click the GENERATE access token button only one time. And I'm even not using the access token after generating it. And then suddenly everything start to work as expected. Webhooks start to work when I create new folder or upload a file.
Any idea ? I can't find this in the documentation ?