yes, most likely the timeline hasn’t been rendered.
sometimes a simple Command R isn’t enough,
unless your FCP is set up for it, it won’t render a lot of the real time playback effects.
even the Render All command (Option R i think) doesn’t render “full quality” real time playback effects unless it’s set up to do so in the Sequnce Menu render controls.
another gothcha here is that with certain types of (non I-frame) media (HDV or XDCam for instance) there can be no render indicators, and yet, FCP has to create new media for an export.
i saw this on my last project, where we’d have a bunch of XDCam clips in the timeline , no effects.
hit “render al” and FCP has to “render” up to 15 frames either side of every edit.
if you haven’t done this, exports of any type can take a long time.
reference files are ok when you’re in a rush, or if you just need something to drop into Compressor or Encoder,
but they are risky: they rely on render files that may not exist after a certain time,
so don’t bet on them working after a week, and always label them “REF” of something, so you know.
they also do export a hard copy of the audio.
if you don’t need the audio, remember to export as “Video Only” on the export page,
then it’ll be lightning fast.
nick