mostly can't rotate external monitor with Display Settings

I have a Dell m3800 running Loki that is fully updated as of today. I use in a Dell U2410 monitor via HDMI. The whole screen can physically rotate, so I also want to set the rotation in Display Settings. Occasionally this works, mostly it does not. For example, if I plug in the monitor, and it shows up as present but disabled, I go to the monitor menu to enable it, and the only rotation option is "None". Then when I enable the monitor, that works fine, and then I have the proper rotation options for that monitor. But when I tried arranging the monitor layout or changing the rotation options, it often does not enable the Apply button. Clicking "Detect Monitors" seems to do nothing.

I then tried `xrandr --output HDMI1 --rotate left`, and that worked perfectly.

I was having issues with sleep/suspend, so I installed bbswitch, turned off the nvidia card, uninstalled xserver-xorg-video-nouveau and blacklisted the kernel module, e.g. `blacklist nouveau`.

Launchpad Details: [#LP1674251](https://bugs.launchpad.net/bugs/1674251) Hans-Christoph Steiner - 2017-03-20 08:19:11 +0000

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