For a project which is associated with ServiceDesk, if a user creates a Service Desk Request (through the Customer Portal), then notifications are sent correctly according to JSD-323.

However, if an issue is created normally by clicking on Create Issue button (same project) or via email through a mail handler (same project, no matter Default Reporter or recognized user), then the Reporter does not receive any notifications at all, including Issue Creation, Issue Updated, Issue Commented, and Issue Resolved.
This does not happen when ServiceDesk is disabled, hence ServiceDesk must have affected JIRA notifications in an unexpected manner.