Processed an NEF in LR4 - sky shows blue spotting that spot removal tool does not fix (clone or heal) - I can't find any of these spots when I load the same file in LR3, and have tried various settings to reproduce the problem in LR3 - normally spot removal works well but not on this file when launched in LR4. I've used LR since the beginning - puzzled why a file that looks fine in LR3 has problems in LR4 that can't be fixed using normal methods.
Lee Jay - I looked at the image that showed the spots - spot removals are normally marked so you can see existing corrections when you turn on the tool. I could find no trace of any corrections. This is one of a series of shots taken over a few hours - some taken within a minute or two - and there is no indication of dust spots or spot removals on any of those I checked.