No operating-system notification

What you see. An alert, a met scenario condition or a fill produced no notification from the operating system.

Why. One of these:

• Tented’s window was focused. By design, only the toast shows then.
• The kind is off in Settings → General (Alert notifications, Condition notifications, Fill notifications).
• The operating system blocks Tented.

What to do. Turn the toggle on, and allow Tented in System Settings → Notifications (macOS) or Windows Settings → System → Notifications. See Notifications.