Wish I could really help with an answer but I saw this happen with early versions of LR but not lately. I think I would see if you can open them in DPP or another converter and on your camera. If you cannot open them in the camera it could be the card or just a bad write from the camera. If you can open them in the camera and DPP it's a LR issue. If it's LR, try moving them from the card again after deleting the offending bad file in LR from the disk.