Hey,
When I try to extract the largest preview from the attached DNG file, I get a pure black (as far as I can tell malformed) tif file. The preview comes out correctly when using the command line tool.
My suspicion is that it is caused by some sort of buffer issue.
Maybe this would fix it?: bertrandom@d70e8d1#diff-4b1bc7e3221372b255f78e300bbc977dR365
IMG_5135.dng.zip
Thoughts?