There are several reasons why an entire Timeline will not Render, or Render completely:
- The WAB (Work Area Bar) is only set for part of the Timeline.
- There are Clips, or sections of Clips, that do not need to be Rendered for smoothest playback.
This Tips & Tricks article goes into more detail on Rendering the Timeline: http://forums.adobe.com/thread/794719?tstart=30
Many thanks. You seem to bail me out of all my PE12 issues. I guess the real rendering takes place as you export your work file to a final media?
You are correct. The Rendering of the Timeline is just to provide the smoothest playback for that Timeline. When one outputs an AV file (Publish+Share), the Clips that are on the Timeline (actually linked, and not actually ON the Timeline), plus any instructions (Effects, Transitions, etc.) are Encoded, often referred to as Transcoded, to produce the resultant AV file.
Good luck, and never hesitate to ask any question here.