My environment is IMAC running with latest MAC OS.
Both in LR4 and in LR4.1 I am having intermittent problems downloading Raw images for my Canon 7D.
The problem doesn't always happen.
I am downloading from Sandisk CF cards, cards that work perfectly in every other environment. Download is via a Sandisk card reader.
2, 3 , 4 images in a batch will not be downloaded by LR, error message :" image not recognized", or similar.
No problem downloading the same batch using Canon software.
I haven't done any extensive checking, but it looks like the problem could be with the Copy and convert to DNG, not the actual download.
I downloaded a batch of images (that LR had problems with ) , using Canon download software (no problems).
I then did a Import in LR4.1, including convert to DNG.
One of the images (previously imported and converted without problems by LR), now was not copied and converted.