Brush stroke not extending to the outer limits of the cursor

Hi...just the last 2 weeks or so I have noticed that whilst using ANY brush tool, paintbrush, healing tool, cloning tool, sponge, etc despite setting the hardest edge the action of the brush doesn't extend to the edges of the cursor / brush thus leaving a reasonable sized area which the brush does not affect as it should, it's a weird effect. I have tried resetting tools, changing all kinds of settings within the brush options, tried different cursors nothing seems to correct the problem. I am attaching a screen grab of a variety of paint brush strokes, the one at the bottom shows the brush size (set to it's hardest) and the resulting paint stroke is visibly smaller than the brush, this happens with every tool that has a brush option. Please help.