Does this mean if I make a totally new profile and sequence using the latest 2.5 that this would not happen?
UPDATE: I tried this, making a totally new profile (typed in the parameters) and totally new sequence in 2.5.2.1 and it still failed to dither after the first frame but dithered properly after that. Guess I will have to use a dummy first frame for a while.
Frankly, I don't know why anyone would not dither every frame. The math, not to mention 20 years of imaging, says that is the proper way to do things. It boils down to right vs. faster, IMHO.