Unable to set mailnickname through AR Sync service

Question

I am running a workflow to create multiple users using AR Sync service. Previously, we were setting one employee attribute through extensionAttribute14, which now I want to change to mailNickname. 
 Note: **We were not updating mailNickname previously 
 Now, after changing the workflow, the user gets created without updating the mailnickname field. 
 I even tried to put the same value in both extensionAttribute14 & mailNickname. It only updates in extensionAttribute14. 
 
 Do I need to make any more changes to update mailNickname through sync service.

Eric Hibar Jr. · Answer

Megha, 
 You wouldn't happen to be in a hybrid setup with EntraID would you? If so, the solution could be pretty simple. Have a look at this KB article: https://support.oneidentity.com/active-roles/kb/4251315/mailnickname-attribute-being-cleared-in-hybrid-exchange-configuration 
 Essentially it just has you disable a built-in policy and potentially create your own to control that attribute. Hope this helps.