If the NRGeditor doesn't start using the native launcher on your linux distro. (for some reason) simply access the path directly and launch it manually from the command line. Open a terminal (Ctrl+Alt+t) and type the following:
cd /snap/nrgeditor/current/
./NRGeditor
In addition make sure that the following permissions are enabled:
Let me know if it work for you...
Alternatively you can grab a copy of the latest version of the NRGeditor for Ubuntu from our download section: My Account (up right hover your username) > Downloads