I just want to add that I have the same problem on my Asus N552VW. I have managed to make it work from day 1, so hopefully this can help someone until the proper bug fix is provided.
I have a laptop and an external monitor plugged via HDMI, everything is turned off. Simply turn on the laptop and load the OS, input your login/pass and get into system. Now close the laptop lid, then turn of the monitor.
This are the only steps I can make an external monitor work with 20.04, kernel 5.4.
I just want to add that I have the same problem on my Asus N552VW. I have managed to make it work from day 1, so hopefully this can help someone until the proper bug fix is provided.
I have a laptop and an external monitor plugged via HDMI, everything is turned off. Simply turn on the laptop and load the OS, input your login/pass and get into system. Now close the laptop lid, then turn of the monitor.
This are the only steps I can make an external monitor work with 20.04, kernel 5.4.