It sounds like either it's permissions on the OM Ent user, or the user they discovered it with, as the commands provided work on our end. 
Hello,     I manage multiple Dell PowerEdge Servers (a mix of R620's, R630's, and R640's).  Recently, we have decided that we would like to change the group that has Administrative access to login to our iDRAC's (this is an Active Directory group).  Is there an easy way to do this across multiple servers, or do I need to resort to doing this manually?  Just looking to see if there is a way to do this using OpenManage Essentials, OpenManage Enterprise, or another method.  I looked at pulling down a .cfg file, editing it, and uploading it, but I don't know if this is a good method since I'm only really changing this group, I'd hate to have to either pull down the config file for each server and modify only that.  Is there a way to comment everything else out of the config file and upload that to multiple servers, basically only updating one section of the config, or will it break something, fail to upload, or clear everything else out?   Just looking to avoid updating 75+ servers manually if possible. Thank you!
Update AD group on Multiple iDRACs