You have to convert all 1080i29.97 media to 23.98, pulling up all clips using AE or other app like DVFILM-MAKER, before import it from M100.
You could perform a 'force' import to standard and codec from M100 (selecting it in the import window), but it isn't a clean interpretation of the movement, because it do not pull the cadence of the frames.
What are your camera/codec settings?
Are you working at 23.98 or 24 fps?
Fermin Branger
ALFARERIA CINEMATOGRAFICA
Caracas, Venezuela.
http://www.alfareriacine.com