This has bugged me since I upgraded to version 4.x. I noticed that the app does not stay in the dock on startup and found a workaround that appears to already exist in iCUE. Assuming iCUE is in the default location, close any running iCUE, then paste this in to terminal:
Alternatively you can navigate to the path or automate the whole process by creating an app using Automator.app -> create app -> select "run shell script" and paste this:
and save it in your applications folder. It kills iCUE if it is already running and opens the helper app in the system tray
