I created an EYE on the Main Stage and then turned it into a Movie Clip Symbol, and within that, nested some eye lid and pupil movements. So its set up like this:
-pupil (pupil is also a Symbol)
Once the playhead reaches the frame where the EYE symbol starts, the playhead moves through the timeline but none of the animation nested in the symbol actually plays. All I see is the static image of the first frame in the nested symbol. I thought that maybe I needed to extend the size of the EYE layer on the main stage and add more frames. I added more frames than the nested animation actually had and still no animation showed on the main timeline..
that's expected if your scrubbing/playing the timeline in the ide. if you test, you should see your movieclip's animation.