I also have this problem. Whenever I try to use terrain paint it doesn't apply the paint and for some reason it also deletes all other terrain paint that was on the lot originally
I too have this issue, regardless of what type of lot I try to alter or what type of grass/we I try to paint. I can only paint one blob and then when I try to drag it (like to make a path or larger spot) it all disappears except where the cursor was last.
I also have this problem, it is driving me insane, please find a fix soon.
