Final Cut Pro does not support clips or sequences longer than 12 hours. Importing or capturing clips longer than 12 hours will produce the message "File Error: 1 file(s) recognized, 0 access denied, 1 unknown."
Keep individual clip length to less than 12 hours to avoid this issue.
So sayeth Apple.
It's strange that that is the limitation given that some timelapses are far far longer than a mere 12 hours. I'm surprised this hasn't been mentioned before. A friend of mine had a 24+ hour clip once and thinking about it I remember him mentioning a limitation like this. I wonder if it has anything to do with FCP only addressing 2.5 Gigs of ram at a time, if that still applies.