Comment 3 for bug 1517046

@yuval can fix the issue by creating a ~/.xprofile file with the xrandr lines (change the lines to match your configuration):

xrandr --newmode "1920x1080" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
xrandr --addmode eDP-1 1920x1080

use "cvt 1920 1080 60" to get the --newmode line

I am getting similar results as OP with an HP 2711x using Ubuntu 17.04 beta. The monitor is detected but it doesn't list the native 1920 x 1080 @ 60Hz resolution. Adding the resolution with xrandr makes the external monitor go black, but the displays application still shows it on and connected.

Two other new Dell monitors won't detect at all, however one is using USB-C->HDMI to HDMI->DP adapters which I think is causing issues. The other is using Thinkpad's DisplayLink with the latest drivers.