Greeter looses focus on password field after resume

When laptop is been suspended from greeter screen, password filed looses focus after resume.

Steps to reproduce:
1. Boot laptop to greeter
2. Press power button -> dialog for shutdown/suspend will appear.
3. choose 'suspend', wait until suspend is done.
4. Press wake (or power) button to resume laptop.

Expected behavior:
typing will put characters into password field

Actual behavior:
Password field have no focus and all input is ignored.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: unity-greeter 18.04.0+18.04.20180314.1-0ubuntu2
ProcVersionSignature: Ubuntu 4.15.0-32.35-generic 4.15.18
Uname: Linux 4.15.0-32-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CurrentDesktop: X-Cinnamon
Date: Thu Aug 30 16:39:16 2018
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-xenial-amd64-20160624-2
EcryptfsInUse: Yes
InstallationDate: Installed on 2017-06-22 (434 days ago)
InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary 20160624-10:47
SourcePackage: unity-greeter
UpgradeStatus: No upgrade log present (probably fresh install)