Kernel does not report lid state change; it stays open all the time

[Andriy Beregovenko]

I have a laptop Dell Latitude 5480
Ubuntu 20.04 LTS is in here.
The main problem is that laptop does not go to the sleep when I'm closing lid.
I dig into the problem slightly and figured out that actually state of lid is always open even if it is closed.
I checked state of lid in a following way:

  cat /proc/acpi/button/lid/LID0/state

with a following results:
  state: open

Is there a way how I can debug further?

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-oem-20.04 5.6.0.1028.24
ProcVersionSignature: Ubuntu 5.6.0-1028.28-oem 5.6.19
Uname: Linux 5.6.0-1028-oem x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.9
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Thu Sep 17 21:01:24 2020
InstallationDate: Installed on 2020-09-09 (7 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
SourcePackage: linux-meta-oem-5.6
UpgradeStatus: No upgrade log present (probably fresh install)