In order for the ThreatLockerService to be able to retrieve your active directory groups, the Domain Computers must be a member of the Windows Authorization Access Group.

Steps for Allowing ThreatLockerService to Retrieve your AD Groups:

1. Navigate to your Active Directory Users and Computers.
2. Under your domain controller click on the Builtin folder.
3. Toward the bottom of the folder right click the "Windows Authorization Access Group" security group and click properties.
4. At the top of the properties window click the Members tab and then add a new member.
5. In the "Enter the object names to select" add the Domain Computers.
6. Click Apply and okay. 
7. Restart the ThreatlockerService from the Threatlocker portal.