Do you know if this is the same for Lightroom 5.7? I do see the update DNG preview and metadata option. I use Adobe DNG Converter which has preferences shown in this image.PS: If you shoot RAW on DJI drones, usually you have to run the DNGs through Lightroom and use Metadata --> update DNG preview and metadata, else the DNGs will not be properly losslessly compressed and will occupy more space than they should.