I recently built a new mac running El Cap. Installed Lightroom 6 catalogue from backups, and installed my images on a drobo NAS. Lightroom are right up, Told it to use new catalogue, pointed Lightroom to the top folder on the Drobo where my images were, and all images where there, but the thumbnails were grey. Rebuilt all thumbnails using Library - build thumbnails. All looked good, except now all images have an up arrow at the top right. Clicking on it yieldsThe metadata for this photo has been changed by another application. Should Lightroom import settings from disk or overwrite disk settings with those from the catalog? Since the images were not edited last night, I'm confused. Whichever option I select results in wide horizontal black bands over the images, so my images are now unusable. Help!!!!
Can you post a screenshot of the "black bands"