I haven't bought anything from them but I know a few folks who have and they have nothing but good things to say about them. I know they regularly have a lead time in there molds, so maybe it's just that.
Im by no means an expert, but as far as ideas, have you tried adding a drop of worm oil to the parts that will not fill in? Also maybe I miss reading you post, but I always shoot my plastisol above 300, probably closer to 320.