Hi,
Same error for us:
08/06/2019 5:26:43 PM alert2 WKF-560043 Error while sending notification with delivery template 'alertAssignee'.
08/06/2019 5:26:43 PM alert2 DLV-490055 Failed to load delivery ID 3611 into the cache: This delivery does not exist, has been deleted or the login does not have the required rights.
After giving "READ data" access to the 3 following folders: /Administration/Campaign Management/Technical delivery templates/, it works
Thanks!