Attached Link: http://www.runtimedna.com/mod/forum/messages.php?forum_id=43&ShowMessage=154576

This can happen with standard MAT pose files, that leave unconnected nodes in the material room. After applying such a MAT pose, use the "Remove Detached Nodes" (press shift while clicking, to apply it to all materials at once). After that the file should be completely written to disk.