Troubles getting leftwm running

I am currently running bspwm and am trying to get leftwm running. It appears it is not as straight forward as bspwm.

What I have done is set the following in configuration.nix:

services.xserver.windowManager.leftwm.enable = true;

I also created a default config.ron in ~/.config/leftwm.

However, when I log into leftwm, none of the keybindings work. It looks as thoughleftwm start (I see some left* processes have started), however ps reports lefthk-worker as defunct.

What is the trick to getting it running?