@axellejamous I just ran into this black screen issue too.
I figured out that the local electron display will only work if the config.js contains:
address: "localhost"
I was running with the following and getting a black screen
address: "::"
Instead of using the built in display I am going to launch chromium myself in --kiosk mode. I need the MM to listen on all interfaces so I can see and debug from a separate machine.