I think something happened recently with the data Canvas sends via its external app configurations. When you choose "Public" as the privacy setting for an external app configuration, it used to be that Canvas would send across a panoply of information in the LTI launch request, including the email address. However, now, this information is no longer sent across. By selecting "Email-Only" as the privacy setting, the email is sent. Unfortunately, many of our customers interpreted "Public" to mean everything was sent (which it used to be) and now that is no longer the case.