Yep, after rebuilding the dng’s with no preview in lightroom, it seems like there is some absolute minimum like 128x128 preview. And that is all RC can read from the 42mp DNG. So unless you know that the jpg previews build into your raw files are full res and with the processing you want (noise reduction, sharping, ect…) your better off exporting full quality jpgs. I don’t think I’ll be using tiffs anymore as there is no quality difference and the downside is speeds much slower and massive files, 4 times lager than the original raw files. I have found that compressing them either zip or lzw only increases the already slow tiff RC processing time, and the files are still much larger than the original raws.