Chat - can't select machine when user is logged into more than one computer

Chat - can't select machine when user is logged into more than one computer

When I use the chat tool, for some users, I can view a dropdown list of machines they are logged into and select the machine I want to connect to. For other users, I can view a partial dropdown without any machines listed. There doesn't seem to be any pattern. For most users, I can view the machine dropdown, but this is a problem if I am remote controlling one of the machines they are logged into, and I need to communicate with them. 

                  New to ADSelfService Plus?