External monitors--limited working permutations

[Michael Greenburg]

"Displays" in the Gnome Control Center doesn't seem to be working.
When I connect an external monitor (Dell P2415Qb) to my laptop (XPS 13 touch screen), most of the "Join Displays" options do not work: when I click "Apply" after changing resolution or display arrangement, the external monitor goes to sleep. When I move the mouse into the region that the monitor should be, it seems to go into that region--it feels like although the laptop knows that the monitor is there, the monitor doesn't get a signal.
The only permutation (besides setting display mode to "Mirror") that I have found to work (i.e. the external monitor doesn't go to sleep) involves setting the resolution to 1600x900 on both the laptop screen and the monitor. This only works when the monitor is to the left of the screen. When I try to put display 2 (the monitor) above display 1, or of course change resolution, the monitor goes to sleep.

I would expect that any permutation of screen positions and resolutions that is allowed by the GUI would work, i.e. the external monitor should not go to sleep after applying changes when "Join Displays" is selected. It's odd that only 1600x900 is allowed (both the laptop screen and external monitor can do much better), and that the relative positions of the screens makes a difference.

Ubuntu 18.04

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-control-center 1:3.28.1-0ubuntu1
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: Wed May 2 11:15:56 2018
InstallationDate: Installed on 2018-04-27 (5 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_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-control-center
UpgradeStatus: No upgrade log present (probably fresh install)

[Sebastien Bacher (seb128)]

Thank you for the bug report, could you provide the output of "xrandr" and the journalctl log after getting the issue?

[Michael Greenburg (micgre93)]

Upon restarting, I was able to get the monitor above the laptop screen, but only after a few attempts; the behavior doesn't seem to be deterministic--sometimes one permutation will work, sometimes it won't.

Here is the output of xrandr:
Screen 0: minimum 320 x 200, current 1600 x 1800, maximum 8192 x 8192
eDP-1 connected primary 1600x900+0+900 (normal left inverted right x axis y axis) 294mm x 165mm
   3200x1800 59.98 + 59.96 59.94 47.99
   2880x1620 59.96 59.97
   2560x1600 59.99 59.97
   2560x1440 59.99 59.99 59.96 59.95
   2048x1536 60.00
   1920x1440 60.00
   1856x1392 60.01
   1792x1344 60.01
   2048x1152 59.99 59.98 59.90 59.91
   1920x1200 59.88 59.95
   1920x1080 60.01 59.97 59.96 59.93
   1600x1200 60.00
   1680x1050 59.95 59.88
   1600x1024 60.17
   1400x1050 59.98
   1600x900 59.99 59.94 59.95* 59.82
   1280x1024 60.02
   1440x900 59.89
   1400x900 59.96 59.88
   1280x960 60.00
   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
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-1-1 disconnected (normal left inverted right x axis y axis)
DP-1-2 connected 1600x900+0+0 (normal left inverted right x axis y axis) 527mm x 296mm
   3840x2160 60.00 + 29.98
   2560x1440 59.95
   2048x1280 59.99
   1920x1200 59.88
   1920x1080 60.00 60.00 50.00 59.94 24.00 23.98
   1600x1200 60.00
   1600x900 60.00*
   1280x1024 75.02 60.02
   1152x864 75.00
   1280x720 60.00 50.00 59.94
   1024x768 75.03 60.00
   800x600 75.00 60.32
   720x576 50.00
   720x480 60.00 59.94
  ...

[Sebastien Bacher (seb128)]

the log has those warnings

gsd-xsettings[1590]: Failed to get current display configuration state: GDBus.Error:org.freedesktop.DBus.Error.NameHasNoOwner: Name "org.gnome.Mutter.DisplayConfig" does not exist