Sometimes proof colors look different from the original image. It is related to the way how browsers handle CMYK color profiles in jpeg images.
If you drop an image into Chrome and Firefox, you'll notice that the latter displays it correctly.
Ziflow's default setting is to display the original image in the Proof Viewer if the file size is less than 10MB. So when you open the proof, it loads that original image. If you open a proof in Chrome and in Firefox, you'll notice it looks correct in Firefox for the reason mentioned above.
In Ziflow you can force all images to be processed, which means that they are going to be displayed correctly in any browser. You can find this setting under Settings > Proofing Settings > Proof Viewer > Other Options > Show original image. Change this to "Always process" and newly uploaded images will be tiled by our system and shown correctly in all browsers.
For more information about this and other Ziflow Viewer settings, please visit this Help Center article.