I had issues installing LR6 on my Mac as the serial number was not recognized. Adobe helped me on that one and after a lot of tips & tricks, they could solve the issue. Now i have issues in the develop mode. If I type a negative number, it does 2 transactions simultanuously namely setting it to minus and immediatly back to zero. With a ctrlZ I get the correction I need. This happens in every field and only on my Mac, not on windows. Anybody any idea?