Icons in "Select an icon" appear as all black when clicked on

[Jason Kau]

After clicking on the current Icon under Edit Laucher or under Whisker Menu and getting the "Select an Icon" or "Select an icon" window with a list of icons, if you click on any icons, they are rendered as black. Happens regardless of theme and happens even with fresh users.

Xubuntu 18.04, XFCE, NVIDIA proprietary driver.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: libxfce4panel-2.0-4 4.12.2-1ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-101.102-generic 4.15.18
Uname: Linux 4.15.0-101-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.14
Architecture: amd64
CurrentDesktop: XFCE
Date: Thu May 28 00:03:50 2020
ExecutablePath: /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper-2.0
InstallationDate: Installed on 2014-05-29 (2190 days ago)
InstallationMedia: Xubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2)
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: xfce4-panel
UpgradeStatus: Upgraded to bionic on 2020-05-26 (1 days ago)