Sounds like it could be a permissions issue. Does the user who is viewing Other User's Account have rights to manage that user? If not, can you (temporarily) enable that and see if the issue is resolved then?
**EDIT**
I understand your response, but from a Mendix perspective, viewing information about users and committing a user entity are 2 distinct things from a security perspective. Just to eliminate the possibility that security is the cause of this issue, can you login as a user who has rights to manage all users and see if the problem is still there? I've included a screen shot of the type user I think you should login as below: