I have exactly the same issue as detailed in this forum post of April 2017.
The reply button is not available there, and no solution is given, hence I must repost here.
Does the issue resolve itself after a few weeks? It is frustrating not being able to post to that thread to seek an answer from others who have had this problem.
It is, as other users there state, near pointless having a Hi DPI monitor in this condition. The gray bands are distracting and annoying. The bands are on the surface of the screen, above the LED, this being visible due to a clear parallax effect as the original post states. My hope is that some kind of burn in might solve it. Information would be appreciated as to whether or not I will need to return this item. It is frustrating that the original unsolved post, above, has been turned off!
Attached image of the white test screen.
I'm not clear on how an adequate photo can be taken of this problem, this perhaps being the reason others didn't do this before. Nevertheless I've taken a photo of the bottom right quadrant on the white test screen, attached.
The bands come and go - I thought they were solved yesterday and this morning they seemed almost invisible, but it seems that whenever white is displayed, the gray bands seem to become more prominent.
I'm hoping that over time it gets less prominent; the improvement if there is one isn't linear, though. I'd be surprised if the attached photo is useful to you, but nevertheless I post it as you request.
UPDATE: I have not been able to upload the image, as your image upload does not appear to work. (please test it and let me know if it works for you).
To further clarify my comment above, it appears the bands are almost impossible to photograph in any case. The camera would need to focus on them and not on the light source itself (the bands are above the light emission surface as stated in the previous post) and my iphone camera is not up to the job, I've tried and it simply can't image them; if you zoom in you see pixels, but not the bands as still visible to the eye in front of me. I'd imagine a superbly advanced camera able to photograph it might exist, but I don't have one.
I find the monitor wonderful and lovely to use, with one (major, quite absurd) proviso - that one does not try to work on any document that has a white background. In that case, on the one hand the high definition of the text is very attractive, yet on the other, the bands given an impression as if it is written on laid paper (the type of paper making which puts horizontal lines on the surface). A bit of an absurd situation to have a monitor where you don't like working on "documents with a white background"!
You save the picture to your windows desktop. Click Reply on the thread, click the Photos icon, click Choose Files, click the saved picture, click Done =
What makes you assume I have a "Windows Desktop"? This is absolutely ridiculous.
On Macintosh, and in either chrome or safari, there is no file upload dialog. I can fill in the filename manually but nothing uploads.
I think I've simply lost all patience and confidence here.
What makes you assume I have a "Windows Desktop"?
* It was a logical assumption based on the fact that the 2015 P2415Q was never tested in the proprietary Apple OS =
I am using Windows 10 and Google Chrome to post those images. Move the monitor to a Windows system so you can upload the BID image.
Forget it. I'm returning this item now, and though I've always bought Dell monitors in the past, and generally been very satisfied, I'll now be looking to a different brand in future.