Navigate to Scala class, file, or symbol not working after upgrade to IntellIJ 2018 on macOS

I just upgraded my MacBook Pro to IntellIJ CE 2018.1.4 from CE 2017.3.4. I'm doing Scala development with Scala plugin version 2018.1.9. I am finding that navigation to a class or file is not working. I can select a class or a file, but the editor focus does not change. Is this a known problem? Is there a workaround?

macOS version is High Sierra (10.13.4).