Displays shows only one display

[Donald Gordon]

Upon upgrading from 18.04 to 18.10, only one of my displays is working.

Only one display shows in control centre. I have two, one connected via DisplayPort, one via VGA.

The VGA works, DP doesn't.

If I unplug the VGA display, then the DisplayPort display turns on. Plug it back in, the DisplayPort display turns off.

XRANDR shows both displays. Confusingly, the VGA display appears as "DP-2" in XRANDR, and the DisplayPort connected display shows as "HDMI-1."

If I manually enable the second display with

xrandr --output HDMI-1 --right-of DP-2 --mode 1920x1080

then the second display starts to work, and it appears in the Displays section of the control centre, as it used to in Ubuntu 18.04.

Here's the output of xrandr prior to manually enabling the second display:

donald@silver:~$ xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
LVDS-1 connected (normal left inverted right x axis y axis)
   1600x900 60.06 + 59.99 59.94 59.95 59.82 40.04
   1440x900 59.89
   1400x900 59.96 59.88
   1440x810 60.00 59.97
   1368x768 59.88 59.85
   1360x768 59.80 59.96
   1280x800 59.99 59.97 59.81 59.91
   1152x864 60.00
   1280x720 60.00 59.99 59.86 59.74
   1024x768 60.04 60.00
   960x720 60.00
   928x696 60.05
   896x672 60.01
   1024x576 59.95 59.96 59.90 59.82
   960x600 59.93 60.00
   960x540 59.96 59.99 59.63 59.82
   800x600 60.00 60.32 56.25
   840x525 60.01 59.88
   864x486 59.92 59.57
   800x512 60.17
   700x525 59.98
   800x450 59.95 59.82
   640x512 60.02
   720x450 59.89
   700x450 59.96 59.88
   640x480 60.00 59.94
   720x405 59.51 58.99
   684x384 59.88 59.85
   680x384 59.80 59.96
   640x400 59.88 59.98
   576x432 60.06
   640x360 59.86 59.83 59.84 59.32
   512x384 60.00
   512x288 60.00 59.92
   480x270 59.63 59.82
   400x300 60.32 56.34
   432x243 59.92 59.57
   320x240 60.05
   360x202 59.51 59.13
   320x180 59.84 59.32
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 connected (normal left inverted right x axis y axis)
   1920x1080 60.00 +
   1600x1200 60.00
   1680x1050 59.88
   1280x1024 75.02 60.02
   1440x900 59.90
   1280x960 60.00
   1280x800 74.93 59.91
   1152x864 75.00
   1024x768 75.03 70.07 60.00
   832x624 74.55
   800x600 72.19 75.00 60.32 56.25
   640x480 75.00 72.81 66.67 59.94
   720x400 70.08
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 521mm x 293mm
   1920x1080 60.00*+
   1600x1200 60.00
   1680x1050 59.95
   1280x1024 75.02 60.02
   1440x900 59.89
   1280x960 60.00
   1280x800 74.93 59.81
   1152x864 75.00
   1024x768 75.03 70.07 60.00
   832x624 74.55
   800x600 72.19 75.00 60.32 56.25
   640x480 75.00 72.81 66.67 59.94
   720x400 70.08
DP-3 disconnected (normal left inverted right x axis y axis)

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: gnome-control-center 1:3.30.1-1ubuntu2
ProcVersionSignature: Ubuntu 4.18.0-10.11-generic 4.18.12
Uname: Linux 4.18.0-10-generic x86_64
ApportVersion: 2.20.10-0ubuntu13
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Oct 20 08:10:51 2018
ExecutablePath: /usr/bin/gnome-control-center
InstallationDate: Installed on 2018-08-13 (67 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
ProcEnviron:
 LANGUAGE=en_NZ:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_NZ.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-control-center
UpgradeStatus: Upgraded to cosmic on 2018-10-19 (0 days ago)

[Donald Gordon (don-dis)]

OK so I've just found out where my extra displays were hiding. The Button that says 3 Viewsonic Corp ... can be clicked on to choose another monitor.

[Donald Gordon (don-dis)]

Which is to say this is more of a usability issue than a "this functionality is unavailable."