It appears that android13 (SDK33) now requires a runtime permission for setting local notifications:
https://developer.android.com/develop/ui/views/notifications/notification-permission#user-choice

I get this error when running the LocalNotifications.schedule method: Permission not granted..

I've tried just adding this permission: <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/> but nothing changes.

If I grant notification permissions to the app via App info > Permissions then everything works fine again.