[Gianni Patrizio]

Check your field dominance of FCP timeline. The reason why the transitions are jumpy is because those areas are being rendered to the field dominance of your timeline and other footage without effects plays back fine. What is happening is your transitions are being rendered with the incorrect field dominance compared to the footage you are placing in the timeline. If you go into Final Cut and then under Sequence then Settings change the field dominance to upper or if it is already upper try lower.