I've had this happen too. I solved it by rendering without GPU acceleration.
Thanks! Will give it a try
The problem occurs when two clips that both have Shadow/Highlight adjusment with different values are crossfaded. You get this light dark bands of flickering in the crossfade. It looks horrible.
SOMETIMES, disabling GPU acceleration works. Not always.
Setting the clipping amounts to 0, as opposed to the default of .01 will help with the clip flickering, but NOT the crossfade flikering. It will not help
Using Opacity keyframes as opposed to the Crossfade Video Transition Effect will not help.
The only sure way to solve the problem is to make INTER clips. Render the two clips seperately with all shadow/highlight effects, then replace the clips on your timeline with the rendered clips and THEN crossfade them.
Also, for those of you that simply notice the "sky" in your scenes flickering when using Shadow/Highlight Adjustment, make sure to set at least the Black Clip from .01 to 0. This will stop that annoying flicker throughout the entire clip.