Issue:
A requested name change or e-mail address change has been processed by IMS but is not appearing in the Global Address List (GAL) in Outlook.
Explanation:
Changes to the GAL can take up to two days to appear in Outlook. This is because Outlook is configured in most cases to operate in "cached mode", which means Outlook only updates its copy of the GAL once a day at a random time during the day. Furthermore, the master copy of the GAL that Outlook downloads from Office 365 is only updated once a day. Therefore, you will not see the updated information in your address book until after Office 365 updates its copy of the GAL and then your Outlook subsequently downloads it.
You can confirm what's in the "live" GAL at any time by logging into OWA (https://outlook.office365.com) and checking the address book there. If it's shown correctly there, you can rest assured that the updated information will be downloaded by Outlook clients within the next day or so.