Optical Flow Bug

Hey,

So I have been working on a project where I use some speed ramps, and instead of using frame sampling, I see better results with Optical Flow. 

On this new project i'm working on, there are 3 clips, where I use optical flow, where they bug out. The opctical flow creates something like a ghost frame above the last one, and I can't see to figure out why, and how to get rid of it.

Thanks!