iPad mail swoosh sound gone missing

An iPad running iOS 12 has lost its swoosh!

Apple Mail would make a swoosh sound when mail was sent. But a couple of days ago it stopped. The sound is on, (not muted.) I go to sounds > sent mail classic etc and can hear the swoosh no problem, but not when I actually send mail. Nor if I change the sent mail sound to one of the other sound options.

iPad volume, and sent mail sounds are the only solutions I have found, but do not apply. Is there anything else to try?

Edit - I now see that lots of systems sounds are not working. Lock and keyboard are set to green but do not make system sound.

All volumes are set to max. Anything else to try?

General > Reset > Reset All Settings

Solved the problem with a hack. Which just means iOS does not do what you tell it, and needs to be reset as it is not written properly. Frustrating, but would have liked to know why the sounds were not sounding