This issue is seen in a domain with multiple Domain Controllers (DC). Some users are not seen in the Exinda under Configuration > Objects > Users and Groups.
Note: In this scenario, some users are correctly pulled by the AD connector, while others are not. If there are no users at all, please refer to Unable to See Traffic Analysis Based on Users and Groups After AD Integration.
This article details relevant information to keep in mind in such cases.
If some of the users do not reside on the DC on which the AD connector is installed, those users will not be seen. Make sure that Exinda's AD connector is installed on a DC where all the users reside. This might mean installing the AD connector on more than one DC if there are cases where certain users only authenticate against a specific DC, and there is no server that can bring in all of the DC logging.