Unflip mouse buttons in Microsoft RDC client
Not sure if this would help but it was a strange find when troubleshooting the below issue:


Shut off wireless mouse
Connect USB mouse
Check mouse settings to be sure primary button is set to Left, exit settings
Disconnect USB mouse
Reconnect wireless mouse


In my situation the user was using a new Magic Mouse and MS RDC 2.0.1.  In MacOS the buttons work correctly but when the user logged into their RDC session the mouse buttons would switch as if it were taking settings from somewhere else.  My theory is that the USB mouse settings had been set to primary button: Right and when you connect the Magic Mouse you can no longer access the same configuration screen but RDC seems to still be using the settings.

Hope this helps!