Watchers on Issue not Receiving Notifications After Comments
Symptoms include inconsistent notifications being sent. SMTP server can be setup correctly with permissions correctly configured. After adding a watcher to an issue, adding a comment will not generate a notification to the watcher.
This has only been known to occur on systems using a MS SQL database.
During system configuration changes (upgrades, migrations), if the database schema name is changed or empty, it can cause inconsistencies in the database and cause it to not be updated correctly. This can cause notifications to not send to watchers.
To correct this issue, please refer to Incorrect MS SQL Schema Used to correct the schema name.