If you shot in 24P (not A), then you should be editing in a Standard DV preset, not a 24P preset. And export out as normal DV for Encore. Things should then work as expected.
DVD's 24 fps capabilities are for film based material that hasn't been telecined before hand, instead relying on flags in the code to tell the DVD player how to do it during playback. Your footage was telecined in the camera before it was recorded to tape.