When this is happening I black out the matte I’m feeding into that action layer when I want it transparent, BUT it’s not elegant, takes away the ability to use the material node trick for multiple surfaces transparencies, and forces me to just to be hopping in and out of the action. I wish flame would just do that for me. But I don’t know enough about how it works to know if the two can really be separated?
This is interesting that this is a solve
Is motionblur using multiple calculations between frames? So even a one frame animation from 0% to 100% has tweens and if using default curve we see an animated fade up but switch to constant and there is no curve even in the motion blur tweens.