just unboxed my new monitor yesterday.
I tried using the DP and Mini DP cable and i just keep getting the No mDp or No Dp.
This is attached to my imac late 2012 with Mac Sierra.
I called Dell - 4times yesterday within 1/2 hour. I got transferred 4 times back and forth to wrong departments and disconnected twice. One of the worse experiences I have ever had. Honestly almost enough to return the monitor! IS this typical.