In some cases MM won't allow itself to be controlled unless it is run as administrator.
In general Windows will not allow any program to talk to a program that has higher privileges than it has, so in order for VC to talk to any program that is run as administrator, VC also needs to be run as administrator.
Some versions of MM had a bug (I think it is fixed now) where it would require admin privileges to run because it was trying to modify file associations on start-up, so then VC would also need to be run as admin in order to talk to MM. In this case I think maybe there is/was a setting in MM to tell it not to do that.
Usually you can run MM and VC as admin only once and control it this way, and this kind of "breaks the ice" after than you can close both MM and VC and then run them both normally and they should work, but this does not always work.