Smart object error (linking to incorrect object) in .psb file under CC 2017

I'm working on a fairly large/complicated Photoshop (.psb) file with several dozen smart objects embedded. Today, out of the blue, suddenly several smart objects began referencing incorrect smart object sources. So now I have the wrong elements appearing in wrong locations on my design. This is a huge pain in the ass as now I have to go back and rebuild those smart objects. I project this will set me back at least 2 hours in my design work. NOT HAPPY WITH THIS.