When clips are imported / moved into time lines the audio and video are not linked. The UNLINK button is gray / inoperative, and right clicking on the clip does not give link or message about relinking. All links must be done manually, which can't be as designed.
All CC updates are current.
PPro CS6 will not open a CC project; says file is damaged.
Try clicking the Linked Selection button in the upper left section of the Timeline, or press Option+L. If that isn't working, we'll need more details about your workflow, system, etc.
Good. Thank you, Kevin. The linked selection was not checked.
At least I think that must have been the problem, although it hasn't been
loaded for several days.
With that not checked there are a number of goofey combinations with
Great! Yes, Linked Selection can have the opposite behavior you are used to if it is engaged and you aren't aware of it. Now you know where to go if you run into that kind of trouble again.