Thanks for trying that @FOCO-Lars! The only other thing I can think of would be app permissions, bluetooth interference, or a 3rd party security/ cleaner app that might be blocking these notifications/ sounds. If the notification is making it to the IPad and the sounds are not playing, perhaps check the different volume controls as well.
The next best step, if the above does not improve your experience, would be to reach out to our support team, at 800-656-1918, for more in-depth troubleshooting.