The first point to check would be if the person has access to the rest of the app she isn't receiving the notifications. If that doesn't resolve it then try using the default notification email like mailto:[email protected] and see if it works. If that doesn't work might be an issue within the notification system. I ain't sure if they've a limit of notifications.
She does have access to the rest of the app. But I have several others who do not have QB logins or roles, but can still receive the email about changes to dates, etc.
I also checked the default setting and it's the same on all the apps she is to receive from.
