We try to setup page tab using this link https://www.facebook.com/dialog/pagetab?app_id=XXXX&redirect_uri=YYYY App Id is provided, redirect uri also. While we have Page Tab feature enabled in app settings for our app, app itself is in live mode, we are logged in in Facebook with user who have page full control access, app has pages_read_engagement advanced access and pages_manage_metadata standart access. But still while we try to use this link we get an error: You must have permission to add apps to at least one Facebook Page to perform the requested action. What's missing in this case to make it work?