I have been using Lightroom for over a year now and I have about 15,000+ photos. I haven't had any problems importing until the last update I did. Since this recent update, when I import from my card or from my external HD, the images all show up and then one by one begin to disappear. I watch as the histogram in Develop changes from the original information to all black. I am so confused and I have lost an entire evening of editing time that I desperately needed. Has anyone else experienced this? I am working on a new Mac and using Creative Cloud Lightroom.