I am using Linux Mint 18.2 and Android Studio 3.0. I started my avd nexus 5 oreo, it's running but not working computers keyboard. I couldn't write anything. Only when i can write something about hundred times try with mouse right and left click. It's silly. I check avd config.ini. Thats true and see hw.keyboard=yes.
I think it can not focus on the emulator window and so its not writing.
Like i sad the problem is emulator window is not focused.
I found two solution.
Right and left keys of the mouse to be written in the text area click quickly 3 or 4 times. (So the window focuses, if you look at the window title it will be understood. Note: You have to do this every time)
Go to your Window Manager, find Focus tab, Change Focus Model -> "Focus follow mouse". (Permanent solution which Paul Freez's answer -> https://stackoverflow.com/a/42720450/4300071)