We are piloting a new desktop based upon Windows 10 and Office 2016 Pro Plus (not 365). We have AD configured to show employee photos.
For the first day or so after the new image is deployed for a user, the "toast" notifications from Outlook for email include the employee photo, if one is available. Afterwards, the photo in the toast notification is replaced by the Outlook icon. This is consistent and reproducible across a wide variety of PCs and users.
Any ideas on what could be happening?