Dock not shown in second monitor except by pressing SUPER

The dock is not visible in second monitor except when I press SUPER key.

The dock's configuration is set to "All monitors" but even when set only to my second monitor the problem also happens.

Furthemore, I tried to use 'mirrored' monitors and the dock is not shown in any of them!

$ lsb_release -rd
Description: Ubuntu 18.04 LTS
Release: 18.04

$ apt-cache policy gnome-shell-extension-ubuntu-dock
gnome-shell-extension-ubuntu-dock:
  Instalado: 0.9.1
  Candidato: 0.9.1
  Tabela de versão:
 *** 0.9.1 500
        500 http://br.archive.ubuntu.com/ubuntu bionic/main amd64 Packages
        500 http://br.archive.ubuntu.com/ubuntu bionic/main i386 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-shell-extension-ubuntu-dock 0.9.1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun May 13 14:12:06 2018
InstallationDate: Installed on 2018-04-27 (16 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=pt_BR.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-shell-extension-ubuntu-dock
UpgradeStatus: No upgrade log present (probably fresh install)