Notes app on iPhone SE is broken

My wife recently updated the OS on her iPhone SE and now the Notes app is borked. The app opens, but is completely blank - no notes visible - and the screen is unresponsive. She’s tried deleting and re-installing, but nothing works. The Notes are in iCloud - she can see them on her iPad and the iCloud settings on her phone says they are there - but they don’t appear on her phone at all.

Any suggestions?