For some reason the New File shortcut isn't binding to super+n on ST3 3012. It's in the default keybindings and I don't have a user keybinding overriding (also tried removing my user keybindings just to test). It also doesn't show up as a keyboard shortcut next to New File in the File menu.
Here's the keybinding from default, should work, right?
Have you tried turning on logging (in the console enter sublime.log_commands(True)) to see what command is being run? Though a user defined keybinding may not be overriding it, a plugin might be.