Yep I've made the stupid stupid mistake of editing ProRes footage with the wrong sequence settings. Have edited a two minute short with the DV PAL settings by accident (I know, I know). Anyhow I have made a sequence with the correct settings now, and when I play the raw prores footage in this NEW sequence it works fine. The trouble is when I copy-paste the old edit in it plays choppy. Now I know it's going to be out of sync which is annoying but won't take too long to re-do (not many cuts and very short film) but it won't play normally at all. even AFTER removing the Distort and Basic Motion attributes.
What I don't understand is when I put raw footage in this new sequence it works FINE, but when I copy the SAME FOOTAGE from the OLD sequence (with the dodgy settings), it plays very choppy even after removing the attributes. Does this make any sense at all?