Libraries Disappearing after restart

I've been teaching Final Cut since 2000. In the last 24 hours I've had two instances of students logging in after a restart and their library will be missing. It's nowhere to be found. Not in the movies folder or anywhere else. There are no backups in the backup folder for that particular project but will be backups for other projects. In addition other project libraries have not disappeared. Anyone know a solution?

This happened on two different computers running 10.13.6 and FCP 10.4.3