I tried running "Create Desktop Entry" both from "Tools" in main menu and "Configure" from the splash screen. It shows
Desktop Entry Created You may now exit IDEA and start it from the system menu (restart a session if a new entry seem not to appear).
but after closing IDEA (without manually locking the icon to launcher), the icon is also removed. I have deleted the desktop entry under
~/.local/share/applications according to this thread Stack Overflow: Intellij launcher doesn't work on unity?
Then I tried
chmod 777 /usr/share/applications/jetbrains-idea.desktop
and dragged it to launcher, which still doesn't work.
PATH are both set up correctly.