I recently upgraded to the latest version of Lightroom CC (Ver. 5.1). I use the Brush tool a lot in my images and I don't know if this is a bug, but my Brush size and Eraser size settings are the same. Before, If I made my eraser brush small and my Brush size large, they would stay the same unless changed.
Now whenever I change the size of one of them, the other is affected. Plus, Auto Mask is the same too. I just want Auto Mask on the eraser brush and not the actual brush.