I have just downloaded Lightroom Classic CC and the catalog seems to be linked ok but everytime I click on a photo the photo disappears and becomes a different photo entirely! boy this is scary! Any suggestions?
Are you talking about the Grid View of Library? Loupe View of Library? Develop view? Navigator Panel? Can you give us some idea of where you are clicking and where you are seeing the behavior? It would help us diagnose what you are seeing.