When there’s multiple X sessions (or Wayland sessions) active on one computer, with the same person logged in on them, and sublime text 3 open on one, it is impossible to launch sublime text 3 on the other.
2 sessions open, “local” (standard desktop session) and “remote” (X2go/NoMachine session).
Sublime Text 3 is open in “local”.
Attempt to open ST3 on “remote” using start menu shortcut or command line “subl3 -n .”.
ST3 opens on “remote”, either with a blank window or (in the case of the command line) in folder mode pointing at the current directory.
ST3 opens on “local”.