I imported a nef image into ACR and made some global adjustments. I decided to use the Adjustment brush, which I hadn't used before, and made some adjustments to the sky area - saturation - of the image with a feathered brush. It was a large feather. I then imported the image and the sky showed large block type shapes similar to pixels but many times larger with no difference to the saturation. Deleted the image and re imported it from ACR with the same problem. I am experienced in using ACR but this was the first time using the Adjustment brush because my normal workflow is to use Viveza 2 on the rendered image in Photoshop. Any ideas where I am going wrong? TIA