1) Did you ever hit the relight (little sun icon)? Your very-low y (elev) values (third column) as well as the roughness of the screenshot suggest you didn't.
2) You didn't by any chance save your work did you? Normally Wilbur clobbers your data so that you'd never be able to recover it, but if you save expressly as a MTED dte, and double-check each time, you'll be able to save your data.
3) Planck, correct me if I'm wrong, but I thought WRPedit required that the data be truncated to three decimal places instead of the normal 4. WRPtool I know doesn't care.
4) Your node count looked a bit weird. Ie, whats with a 508x508 grid? iirc, maps have to be a power of 2 for cell count, like BIS islands are 256x256, Tonal is 512x512, WRPquad is 1024x1024, and my as-yet-unreleased mess is 2048x2048.
Hope this helps.