Panel screen does not turn on after login if notebook was suspended by closing the lid

[Leonardo Müller]

On Xubuntu 18.04, if it's set on power manager settings to suspend the notebook if the lid is closed, when it's open, the login screen appears but after the login the screen turns off. It was observed with xrandr that no resolution is set. To fix this, I have to do one of these three actions:

1) Use the xrandr command blindly;
2) Restart LightDM from a TTY;
3) Reboot.

When suspending using the Whisker Menu or using systemctl suspend, the notebook panel turns on normally after login. It's happening only when suspending by closing the notebook lid. Maybe it detects no screen connected and then unset all resolutions?

The notebook model page is: https://pcsupport.lenovo.com/br/pt/products/laptops-and-netbooks/300-series/310-14isk/80ug/80ug0000br

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: lightdm 1.26.0-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: XFCE
Date: Fri Mar 1 12:24:33 2019
InstallationDate: Installed on 2017-06-13 (625 days ago)
InstallationMedia: Xubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: lightdm
UpgradeStatus: Upgraded to bionic on 2017-10-20 (497 days ago)