Tracks randomly stopped loading into decks in software

For whatever reason, my Rekordbox software is not loading certain tracks into the decks. Tracks that I have been playing for years, and tracks that I have downloaded as recently as this week. No clue what is happening. I was working on a set Friday evening, everything was just fine. Got back into the lab yesterday, and now close to half of my tracks aren't loading. I can't figure out why.