Changes in user store attributes are not reflected in the Global User of the Provisinioning Directory
This occurs if you change attributes such as Last Name, for example, or a custom field associated with a Provisioning CustomField.
The change occurring from an Identity Manager Task such as "Modify User" out of the box does not go to the Global User.
Identity Manager 14.4.2 CHF01
UserSynchronization and AccountSynchronization are Off in the Modify User Task
Change Synchronization to "On task completion" and "Account Syncronization" to "On task completion" in the IM Task and the change in Custom Field will be pushed from IM to Provisioning Store CustomField as expected when running the Modification by the IM Task.
For more information about Account Synchronization settings please see:
Article 36126 - Explaining IM Task Settings (User Synchronization and Account Synchronization)