Garageband Audio Files Missing after Using 'Delete and Move' command

Working in latest version of garageband and been using the 'delete and move' command to tighten up podacast interviews. I'm noticing that sometimes when I reopen the files get the old "audio file missing" message, and these particular tracks are missing any information within them (the regions are still there as they were, but no sound contained within). Is this a known issue? and is there a workaround? PS - the original audio files that were used to create the tracks are still present in the media folder within the project's "package contents"