Consider the following scenario:
In Exchange Admin Center, you go to Recipients > Contacts.
You create a contact or open an existing contact.
You select Email Options, select an existing email address, and then select Change or Add an Email Address.
You enter a new email address, and select Save.
In this scenario, the new email address value is not written back to the caller window (subwindow). Therefore, the new value is not written to the contact object.
To fix this issue, install the following cumulative update, as appropriate:
Learn about the terminology that Microsoft uses to describe software updates.