We just merged https://github.com/ManageIQ/manageiq/pull/11396 that re-enables ActionCable!
When working in development, it is necessary to set up ActionCable to use the same database as ActiveRecord. To do so you should simply run
cp config/cable.yml.sample config/cable.yml.
This is not necessary for freshly created development setups as this piece of code was appended to the
Have a nice day!