Solution
This issue has been addressed in the following release:
 
Enterprise Vault 12.1
 
The following link contains information about Enterprise Vault 12.1
https://www.veritas.com/docs/000107766
 
Note: For information on how to obtain Enterprise Vault 12 see: How to obtain the license key and installation download for Veritas products

To enable delegate users to view private items once Enterprise Vault has been updated, make the changes described below:

1. In Windows Explorer, browse to the EVSearchClient subfolder of the Enterprise Vault installation folder; for example, C:\Program Files (x86)\Enterprise Vault\EVSearch\EVSearchClient.
2. Locate the web.config file and open it in a plain-text editor such as Windows Notepad.
3. Find the following line and uncomment it: <!--<add key="DelegateCanSeePrivateItems" value="true" />-->
4. Save and close the file.