Interesting side note. They actually work on the broadcasting server, but not on the synced client. The network is fine and all files can be accessed.
Are you remote voice tracking from PlayIt Live to another PlayIt Live instance. This is not supported (as the voice tracks would not record to the correct location). You should use PlayIt VoiceTrack connected to PlayIt Live via the same server URL which will take care of the transferring the audio in the correct format and reduced quality.
I imported a number of new files, and they all appear in the tracklist. I then created a list through a clock. This also works. The clock underan, so I manually added some tracks. They appear, but when I use "Edit segue", they show no content. The amplitude diagram is empty. Playing the file manually through the built in player works and the tune is heard. But voice tracking is now impossible as I cannot hear the outro properly. All other tunes in the hour from the same tracklist work fine.