updating calendar alert tone doesn't work

IPhone 16. Using Settings to change the alerts under Sounds. Can change text messages and ring tone with no problem. But changing calendar alert does nothing. Sound still defaults to value set on my previous phone (setting shows new value). Calendar also syncs to IPad and the change does work there; it’s just on the phone that it doesn’t change. Tried various different sounds and turning phone off. Any ideas with this rather weird scenario?