processing video clips alters the video

normally I process audio off a video clip and import the result back into iMovie, under the original video clip.  today I tried to process the video clip in its entirety.  The result left the video altered in such a way that iMovie was no longer capable of “tweaking” the picture other than editing.  No color adjust, stabilization, etc.  Only split clip.

If possible, it would be good to leave the original video unscathed.