Installed Ubuntu 18.04 LTS on my Lenovo Yoga 3 Pro. Everything is working fine, except the connection with an HDMI external monitor.
Once I try to connect the HDMI eternal monitor everything becomes black, only the mouse in on the screen and the Fn+up/down displays the laptop bright level.
After a while more Ubuntu return to the login screen, visible on both monitors.
How can I solve this issue?