Logic Pro X timeline cuts off audio

Hello,

I've added a pretty long sequence of spoken word clips to Logic Pro x, all in one timeline. I want to output them as one simple audio file (mp3, wav) but the timeline cuts off the audio before the end of the project. Is there any way to extend the audio? It's an audiobook so it is pretty long, several hours. I've never had this problem before. Please see the screenshot to see what it looks like. They greyed out area is silent. All suggestions welcome.

Thanks! Jon