Comment 19 for bug 1573345

I had the same issue, my system:
Linux 4.15.0-45-generic #48-Ubuntu SMP Tue Jan 29 16:28:13 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Steps:
 - connect and external monitor via HDMI
 - disconnect external monitor, select laptop monitor only
 - put system to sleep mode
 - wake up system, enter login and password in prompt
Result:
 - screen is black, i need to connect external HDMI monitor and choose "laptop only" in dialog on external display to activate laptop display
This issue reproduces every time after system sleep. Even if i choose laptop only every time.