I configured an exception for the HelpAssistant remote user so that it would not overwrite the users SSo deteails, but still did it.
Solved! Go to Solution.
Underscores apply only to __vmware_user__ account. For helpdesk you should have:
<User name="__vmware_user__" />
<User name="ASPNET" />
<User name="HelpAssistant" />