Bookmark icons are not shown

The icons of bookmarks are not shown despite I have all borders visible (all items in "View / Borders" submenu are checked).

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: kate 4:17.12.3-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-36.39-generic 4.15.18
Uname: Linux 4.15.0-36-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Oct 9 18:38:04 2018
InstallationDate: Installed on 2018-06-23 (107 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_IL
 SHELL=/bin/bash
SourcePackage: kate
UpgradeStatus: No upgrade log present (probably fresh install)