I haven't used One-Step in a while, but when I did, I always shook the container to help "fluff" the powder. I do that with my PBW too. If that doesn't work, you can always try to use a small amount less than you are currently using.
One-Step always left a film on my bottles when dried; which is easy to rinse off with water after bottling. By definition, you can't clean and sanitize in "one step." I use PBW for a cleaner in hot water, rinse thoroughly with the same temp water, then sanitize with Star San. A large bottle of Star San lasts a LONG time and no film either.