Maybe it's the way you are applying it to the mandrel, or lack of preheating or rods with more air in them. Or maybe you are boiling the softer colors a bit now that you are used to things a bit hotter? Idk.. Over the years I keep edging up the torch hotter and hotter here and there!
have you tried working cooler?
Any chance the release needs a good mixing or needs to be thinned out a bit? Idk...