When applying the Fragment vfx to a clip with premultiplied alpha, the output renders with black background instead of the combined alpha.
Edit: It seems that Heat and Recoloure don't handle the alpha channel correctly, neither.
Edit #2: Also some of the transitions seem to just ignore the alpha channel. Very rude... Respect our alpha channel (e.g. Noisy, Parts, Static, etc.) some only when at 100%, others also during the transition.