Hmm, while looking for the also exported .ter file, it seems the .lwo files did export, and are loadable in PoseRay.
Up to a certain point they are, but the file "x04y02" made Pose Ray crash. Besides that I have the files 'x00y00' to 'x07y02' and only y00, y01 and y02 of every x... So I guess I'm missing half of the heightfield anyways.
Can you look into this?