(MOD NOTE: This post has been moved to align topics. Apologies for any confusion)
Progressive render is a shorthand, quick onscreen approximation of what a final render will look like but it can't do everything a final render does. For example, Toonlines will NOT appear in Progressive renders.
That said, when i re-ordered the groups in your head model the transparency effect was fading in and out as expected in onscreen progressive render. There's some conflict in your groups and decals, I don't think A:M is the core problem, but i also don't have v14 to test with.