Within a Rails app, ActionCable (and therefore WebSockets) did not work when trying to update all users of a new comment.
Expected behaviour was for a user to publish a comment and then a hidden div would be made visible, alerting users that there was a new comment.
How Did I Fix This?
tl;dr: ActionCable requires Turbolinks to work.
Brave developer, spare yourself some time and just re-enable Turbolinks. Learn from my stupidity.