After upgrading to El Captain, when I import photos the photos display normally when selecting which photos to import. Once I select the import button and Lightroom begins the process of importing and creating the smart preview, the thumbnail/preview is totally black. Help!
Could you please check the below link that might resolve your issue:
Please let us know if you are not using Lightroom 6.2.
This did not solve the issue when I "select all" of my photos, and then reset and auto toned. Also, I have never applied auto tone previously on the pics. However, I did get this resolved by selecting each of the 83 pictures individually and selecting reset. The photo then appeared. This is not a good permanent solution however, just a decent work around.