Similarly this is also the case on the Worker master. The Worker grid will show the configured Display as value, but when the record is opened, the first and last name are used on the header.
Comments
I do not believe this has been entirely delivered. I can see the "Display as" value on the Worker record in self-service and on the Worker record shown in the People workspace but in the reporting hierarchy on the left side of the People workspace it still shows as FirstMiddleLast. Also the Position hierarchy (HcmPositionHierarchyView) is still showing the FirstMiddleLast.
Category: Personnel management
Functionality that is really needed in a large organization. This should also facilitate the search function.
Category: Personnel management

Administrator on 11/17/2022 9:15:32 PM
This functionality has been delivered in Dynamics 365 Human Resources on the Finance Infrastructure - please see the feature details here. Worker header control - Human Resources | Dynamics 365 | Microsoft Learn