I purchased this monitor directly from Dell about 3 months ago and has been an issue since I received it. The issue is the LED backlight occaisonally does not turn on after screen resolution / mode changes. This is especially prominent during reboots or startup because of the resolution/mode changes during the bootup sequence going into Windows.
How do I know it's the backlight? The screen power light indicates it is active and not in sleep mode. Additionally when I enable the OSD you can barely make it out on the screen without the backlight on. The only way to resolve this is to turn off the screen for a few seconds and then turn it back on.
What have I done? I've reset the screen back to default settings along with putting it into a few of the preset modes and I can reproduce the issue rebotting a few times or just changing the screen resolutions a few times.
Besides this the monitor works fine and I have no issues with it. But it doesn't appear this issue is going to correct itself via new firmware or drivers and am looking to find a resolution for this.