SharePoint uses the “Preferred Name” property mapped with the “Display Name” property from AD in People search results. Here, I found the root cause of the problem as a user profile, not in sync!
Steps to resolve:
- Make sure in AD, the display name field is set properly.
- Go to SharePoint Central Administration >> Do a full profile import.
- Once you run full profile import, You should see the display name field updated in user profiles.
- Run SharePoint search incremental crawl once for the search results to get updated.