iPhone alarm and timer corrupted

Hoping someone can help as I can't find any online posts re a similar problem. My Apple Alarm and Timer simply do not work at all. I will try to set an alarm by pressing the plus button, filling in all the details and pressing save. It then simply disappears and my iPhone shows no alarms. Similarly, I try to set a timer but the start button doesn't respond. The only things which work are the Stopwatch and the World Clock.

This started on an iPhone 8 (it had worked fine and then it stopped working). When I transferred to a new-to-me iPhone 8 using the "hover you iPhone here" functionality, it ported across the corruption. I visited an Apple shop and they had never seen this issue so they suggested wiping my phone and importing via iCloud.

While I didn't bother on that phone, I have just transferred to a new-to-me iPhone 11 via iCloud (admittedly I did say to bring in apps as well as data) and the same thing has happened.

I can't delete the app because it is an out-of-the-box Apple app. When I tried that, it just disappeared from the screen but was still corrupted in the background. Please can someone advise how to fix the app? I really don't want to have to wipe the phone and then load all my apps one at a time simply to get a working alarm clock and timer!