Speed Ramping Playback Problem

Hi,

I'm using FCPX 10.3.4 to perform some basic speed ramps which I can't get to work properly - help!

For some reason, any clip that is part of the speed ramp that is nominated to play at 100% speed is jerky on playback, not matter how many renders I perform.

For example a clip that I'd like to start at 10%, ramp up to 100% then back to 10% renders the 100% portion a jerky unusable result.

If I remove the speed ramp effect, the clip then plays back normally with no jerking.

I'm using a 25p footage in a 25p timeline, but have also noticed the same problem using 50p clips in a 25p timeline.

Can anybody please explain what I'm doing wrong? Thank you!