Footage is invisible in FCPX

I've opened something I edited about a month ago because I need to change out the music, but now 90% of my timeline is invisible. I use the word invisible because I don't mean black, I mean the clips are actually invisible and I can see the interview clips underneath the connected b-roll footage. Everything is gone, including music, except for the interview clips I used. It's not a primary storyline vs connected clip issue because some b-roll is also on the primary storyline. All of the footage is H264 and I can't find any difference between the interview clips and the clips used as b-roll. If I reveal the clips in the event browser, they're still blank. If I then reveal them in finder, the clips are normal.

The only thing I can think of is when I originally started editing this project it was inside of a different library, and I transferred everything to another Library at some point to reduce clutter, but a simple file relinking should fix any issue that would have caused. The clips aren't read as offline, they're just invisible. I've never encountered this before.

I've tried trashing preferences, making a new user, going to a different computer, relinking all the files, etc. I'm hitting a wall with ideas now. My next attempt will be reimporting an XML of the project. Anyone ever encountered this before? This is a huge bug, and while this project isn't pressing, we sometimes work on show site and have extremely tight deadlines, so I need to know how to prevent this in the future.

I'm on a Mac Pro 2013, 32 GB RAM, Firepro 500

FCPX 10.2.3

OS X 10.11.3

Thanks,

Taylor