Chrome Version: 52.0.2743.116 (Offizieller Build) (32-Bit)
Chrome OS Version: 8350.68.0 (Official Build) stable-channel veyron_jaq
Chrome OS Platform: google/veyron_jaq (Medion AKOYA S2013)

Steps To Reproduce:
(1) Connect the monitor Dell UP3214Q over HDMI.
(2) You are informed, that the monitor is connected.
(3) Tell the dialog to display something on it (mirror, extend).

Expected Result:

Something is displayed on the external monitor.

Actual Result: 

Nothing is displayed on the external monitor. In the source selection of the monitor, there is a red cross next to the HDMI source.

How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)

Always.

What is the impact to the user, and is there a workaround? If so, what is
it?

The external monitor cannot be used. There is no workaround.

Please provide any additional information below. Attach a screen shot or
log if possible.

It works with a Dell P2714T, meaning that the HDMI works correctly.