We only print linked Thumbnail images on WO Travelers, so whether this may be more system wide I can't say.
Occasionally the image will print as an entirely filled black block. Most of the time I would re-print to screen where I could see it was fine, and then when I printed from the Preview it would print fine.
Today I had an entirely different scenario. We have an embedded image (not linked to an item) in the Detail section of the Traveler. This particular WO had three sub WOs (-1, -2 and -3) that were all printed on the same traveler. The image printed black on the first one and correctly on the other two (these were all on the same page). So I printed to screen and printed from the Preview. This time the images in the detail section printed fine, but the Thumbnail view of the linked image in the Header printed all black. Without exiting the Preview I printed again and this time everything printed fine.