This is something that we’ve seen intermittently on our and others' Macs:
From all I can remember, it seems to be triggered only by larger brush sizes. Toggling the brushes panel or the overlay usually clears it up. It seems to be purely a display glitch not affecting the actual brush.
We’ve seen this happening in LR3, so it’s not new. I can’t comment on Win.
Has anyone else come across this?
This happens occasionally to me, and it's quite disappointing as it makes it difficult to use the brush, after all a very important tool in LR Develop Mode. Small or large brush, no difference.
Seems to be prevailing in extremely saturated areas, ex. a flower with very red leafs = there's the problem, but no problem in the more modest green stem of the plant.
Have not been able to find a solution...