yeah something gone wrong there, its a fiddly process. My guess is that you scaled the height (the "multiply" operation in ImageJ) by too much and then when you imported into FAForever Map Editor you selected the "clamp top" option when it complained about "distance between lowest and highest point is higher than 50".
Another possibility is that in ImageJ (if you're not careful) the saturated rendering can affect the numbers. I can't remember exactly what to do in ImageJ to make that happen, but if you mouse-over the pixels you should be able to see what intensity (ie height) the pixel is at the top left of the window. Check that just before you export to .raw. If those numbers seem saturated, then that's the problem.
