gnome-flashback/gnome-panel: bottom right workspace selector will not accept preference change to more than 1 workspace

xwininfo: Window id: 0x2200016 "Bottom Expanded Edge Panel"

  Absolute upper-left X: 0
  Absolute upper-left Y: 1416
  Relative upper-left X: 0
  Relative upper-left Y: 0
  Width: 2560
  Height: 24
  Depth: 32
  Visual: 0x82
  Visual Class: TrueColor
  Border width: 0
  Class: InputOutput
  Colormap: 0x2200002 (not installed)
  Bit Gravity State: NorthWestGravity
  Window Gravity State: NorthWestGravity
  Backing Store State: NotUseful
  Save Under State: no
  Map State: IsViewable
  Override Redirect State: no
  Corners: +0+1416 -0+1416 -0-0 +0-0
  -geometry 2560x24+0-0

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: gnome-panel 1:3.24.1-1ubuntu2
ProcVersionSignature: Ubuntu 4.13.0-21.24-generic 4.13.13
Uname: Linux 4.13.0-21-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
CurrentDesktop: GNOME-Flashback:GNOME
Date: Thu Jan 4 15:32:50 2018
EcryptfsInUse: Yes
GsettingsChanges:
 b'org.gnome.gnome-panel.layout' b'object-id-list' b"['menu-bar', 'show-destkop', 'window-list', 'workspace-switcher', 'launcher', 'launcher-0', 'launcher-1', 'launcher-2', 'launcher-3', 'launcher-4', 'launcher-5', 'launcher-7', 'launcher-8', 'launcher-10', 'launcher-12', 'launcher-13', 'launcher-6', 'launcher-9', 'launcher-14', 'notification-area', 'indicator-applet-complete', 'launcher-11']"
 b'org.gnome.gnome-panel.layout' b'toplevel-id-list' b"['top-panel', 'bottom-panel']"

InstallationDate: Installed on 2017-01-05 (364 days ago)
InstallationMedia: It
SourcePackage: gnome-panel
UpgradeStatus: Upgraded to artful on 2017-10-22 (74 days ago)