I'm experiencing continuous and ongoing issues with corruption of my photos in LightRoom.
For an unrelated matter, I took my iMac into Apple Genius Bar last week, and had a full diagnostic ran on it to check for any damaged hardware.
It came back completely clean and in good order. So that appears to rule out hardware issues.
I had some serious corruption on a few photos a few weeks ago,a nd just last week I took some photos on a different, brand new, camera (Fuji X100s) with a brand new SD card, and have encountered a similar, although not as drastic, scenario, with some sort of digital corruption of the image (see screenshots attached).
The import process does nothing to the image files. Default adjustments are applied, but those adjustments are simply stored in the catalog. The file itself has had no changes applied to it. I think this could be a problem with the card, or the card reader if you use one, or perhaps the cable used to connect the camera to the computer. I believe this is a hardware problem, not a problem with Lightroom. Do you still have the images on the card? Have you looked at the images with other software besides Lightroom?