Video import glitch

I've encountered an odd glitch while importing video to FCP. I can't find an answer to this anywhere on the forum.

I'm making an audio demo. I used ProTools to create it. As it stands, the demo is two minutes long, mostly audio (i.e. with just a blank, black screen for video) but in the middle of it there's about thirty seconds of video footage, matching the audio. So you have a two minute video, mostly just audio with thirty seconds of video in the middle. I hope that makes sense.

I export the videos from ProTools as Quicktime files.

I'm trying to use FCP to finish the video. I'm going to replace the blank screen on either side of the video footage with still images, which I know FCP can do.

However, when I import the video into my FCP session, it only plays up to the point where the actual video footage ends. My remaining audio is gone. This seems to be unique to FCP, because the actual Quicktime movie files play fine.

This is extremely frustrating. Has anyone encountered this before? Got a solution?

I'm using FCP 10.0.6 Trial Version, on an Intel Core 2 Macbook with Mountain Lion.