Re: After Rendering Horizontal thin green bars apear on clips

I don't have a solution, but I get weird green bars like you're describing and they turn out to be nothing, just FCP having a hard time with playback.
I get them when lowering the opacity of a clip made in motion when it is 'fading' to another clip. I know I've seen them in other instances, but this one is the most common. Once I export/compress the clip, the green bars aren't there and it looks as it should.
If there is a setting to get rid of them, I haven't found it.