Second time I've had to back off a new version of yours. My watermark is white lettering with a black background, so that it is readable regardless of the photo. In 5.0.5.1, the watermark is just fine. Just installed 5.0.7.0, and the white letters are fine, but there is no background color being used. I even tried changing the colors to black on white, white on blue, etc., and each time the letter color changed, but the background color remained transparent.

Finally reinstalled 5.0.5.1 and the problem goes away.