After upgrading to Lightroom 6.10 I can no longer export from my DNG files to JPG format (used for Flickr). Flickr reports the JPG files (most of them) are "not an image file". Have done this numerous times before, with versions prior to LR 6.10. Cannot decipher what it is that make some exported JPGs corrupt - some work, some don't. Appears to be a bug.