Why might Due have no alert sounds?
With some system configuration, Due may not play any alert sounds even though your Mac's volume has been turned up. This may happen even as other apps can play sounds normally.
If you're experiencing this problem, follow through the steps below to enable sound for Due on your system.
Open 'System Preferences'
Choose 'Sound' > 'Sound Effects'
- Ensure that 'Play user interface sound effects' (labelled 1) is checked.
- Ensure that 'Alert volume' (labelled 2) is turned up.
If you're still not getting alert sounds from Due, try restarting your Mac. In the next update, Due will be able to play alert sounds independent of the settings above.