I click on some buttons on my mirrored phone but they don’t pass through to the phone. Some buttons include (SEND) on text messages and (ENTER) buttons on several apps, as well as the  button on my lock screen.
Having the same problem; Am using a SM-G900T (Samsung Galaxy S5).
It connects fine (and displays). I can enter text using the keyboard whenever entering a text field on the phone. Back/home/menu works. However, all I get is a finger mouse cursor that does not click or do anything useful.