I'm having the same problem.  Before I upgraded to the latest version, I did not.  I really miss the ability to set the active leg.

I have experienced the same problem after upgrading to the latest version.  Previously, I could set any let as the active leg.  Now I cannot.  Before I connect to FSX, I have the right click menu, but the option to set a leg as active is not there.  I thought perhaps I had to be connected, but after I connect to FSX, I cannot get the right click menu at all.  I am running the program as administrator, as you suggest, but to no avail.  My case is not closed unless there is something I'm not doing that I should do.