Unable to run firefox in headless mode

Question

I am attempting to run Firefox in headless mode. I have made a new profile called 'headless'. Here is what I get when running the command from a terminal in Fedora 30: (I can wait several minutes before cancelling the process but nothing happens)

>>$ firefox -headless http://www.google.com -P headless
*** You are running in headless mode.
^CExiting due to channel error.
Exiting due to channel error.
Exiting due to channel error.

Not sure what's going wrong as I expected it to be as simple as adding the headless option and that's that. I haven't been able to find anybody else with a similar issue.

I'm looking for a more minimal browser for web development in my setup with i3wm. I'm not even sure if headless mode is exactly what I want (i.e. just a panel to display my webpage with no extra UI elements), but it sounds like it is. I've been able to produce a similar result with chrome in kiosk mode (although having to open it and then exit out of fullscreen mode to achieve the effect is unideal), but I would prefer to be able to use firefox.