PSE15 organizer Mac randomly shows files as disconnected?

Have noticed episodes of random files showing as disconnected in my organizer. I've been working with PSE 15 for mac for about year and this only recently started happening. If I shut down program and restart sometimes they still look disconnected but suddenly bounce back as connected. Curiously, If I try to reconnect them in browse, it will show original location of the disconnected file in Apple Time Machine. I've disconnected Time machine back-ups while I'm working but problem still persists. I also tried re-installing PSE 15 and it didn't make a difference. Any advice?