Photoshop color issues dual display setup

Hey there

I'm having a strange color issue in Photoshop on a dual monitor setup where colors change from normal to look desaturated on the second display.

I'm running a Macbook Pro 15" Retina OSX Yosemite with a Wacom Cintiq 27QHD display connected by thunderbolt / mini display port.

I'm a digital artist so I have the Cintiq set up as the primary display; I open a document on the Cintiq, then open a duplicate window of the document and move it to the Macbook display (allocated as secondary display).

There is a color shift as I drag the document to the second display, but that corrects itself when I let go of the window, I'm not sure if this is related or not. At this point colors look normal.

My problem is that as I'm working, the color of the document on the Mac screen changes and goes desaturated, losing vibrancy of color, this seems to happen when I click away from Photoshop onto another application, but not always.

Once the color has shifted to be incorrect, I have to put the displays to sleep then wake them up to correct it. However it happens again shortly afterwards.

This ONLY HAPPENS IN PHOTOSHOP, the same file when viewed in Preview or Finder on the Mac screen looks correct, even when its displayed incorrectly in PS (but only on the second display window)

I thought it could be something to do with color profiles, and I've spent a lot of time changing them, but this happens no matter what the color setting. I thought it could be a cable issue, but then this is happening on the Mac's internal display, not the external connected display.

Is this something to do with the fact that the Mac is set to secondary display or is it driver/setting issues with either PS or Mac OSX?

This is a major problem for me, I've searched forums on Apple, Wacom and Adobe with no luck. I'm posting this to forums on all three sites, so hopefully someone out there can help me!