I was having the same issue, and after reading your whining about frame rates, it dawned on me.. My footage I was trying to timewarp was at 24fps and my comp was in 30fps. Matched comp fps to footage fps and bam. Problem solved. Timewarp is actually incredibly powerful, especially in the current 2018 version, so I figured it was some error on my part, and not the effect.
PS, you can whine anytime. You’re almost always pretty damn helpful! 😀