Missed that they were jpegs, my mistake I haven't used them since, forever!The file I uploaded was JPEG, but I generally shoot RAW and this problem occurs also in RAW files as well.
I'd start by removing LR from my computer and reloading it.
I was thinking about reloading LR ... but am worried that it might be the catalog that is causing the problem ... but I'll reload it one of these days (anyway the catalog is safely backed up in several places. But if it is the bloody catalog, then I'd need to sort (around 40000+ images, which is what I shot since LR5 release) and re-edit ... now that is making me tired already.
Been thinking about this some more.
AFAIK LR will only write back to a Canon RAW file if you update the capture time (and enable the write back option).
If the RAW files are being physically corrupted then I can't think of any scenario in which LR would be responsible for this (I'm not saying it can't happen; but it just seems very unlikely).
A sample corrupt and good RAW file would help.
Adobe are going to ask the same sort of questions already posted here.
I do understand the frustration dealing with an issue like this; but I'd like to suggest again that finding time to do some controlled testing is probably your best bet right now.
- shoot a bunch of images on a camera & card you've had problems with.
- copy the files to you computer
- before importing into LR compare the images on the hard disk to the CF/SD card (you can use diff on OS/X or fc on Windows). If the files don't match, then try changing card reader.
- if the files match, import into LR and see if you get any corruption
You might need to do this multiple times until you can reproduce the problem. It will probably be time consuming and tedious; but there really doesn't seem any other option to me.