Hello,
I am having trouble removing/editing/enabling a Network Access User on my 3.0.0.458 installation of ISE.
I have 5 network users, all of which are used for radius authentication. When I initially set up this instance of ISE I added all of these users, and everything worked fine until about a week ago I noticed authentications were failing, I went and looked and all of the user accounts were disabled. I was able to enable all but one of the accounts, when I go to enable, delete, or recreate it I get this error:

If I go to edit the user, I get this error: (XXXXXXXXX instead of actual username)
Unable to load idMgmtUserAction.do?command=nacUserEditPreload&requireAttributeListing=true&selectedItemName=XXXXXXXXXXXX&selectedItemId=4a2644f7-fb9d-420b-a4c9-8d4a20bbb7f9 status:400
The other 4 usernames are just letters and hyphens, however, this username contains a $. I am assuming this is the problem, however, I cannot remove the user and do not know how to proceed from here. I have tried rebooting my instance of ISE, that did not resolve the problem.
Any help would be appreciated, thanks.