Interferences problem

I'm having trouble with the interferences effect... It seems that whenever I set it to additive it only renders the effect to a small area at the top of the screen then abruptly stops. How can I fix this?

Hmm...funny, this is a huge bug, but it's not in the wishlist. Nor are there any other threads on it I can find. Anyway, it's a known bug, hell if I know what causes it. I suggest using a 50/50 blend and then a 2x fast brightness. It results in slight color loss but you get the same effect.

Added to the wishlist...

Thanks for the help! Your suggestion worked great.