When I try to import photos the source panel shows my selected drive and some upper level folders but the folders that contain the photos are greyed out and don't show and of the sub folders to select. the include sub folders check box is checked. the centre panel says no photos found. this just started happening today I have not had any issues with this before. The photos that I am trying to import can be see and opened in a finder window
Close LR, Restart your computer and try again. I had the same thing happen to me about a week ago. A fresh start of the OS and then doing an import fixed it.
At least it is a starting point. Post back if it doesn't work.
I did this a couple of times. The last time I let it close for a longer time and this seems to have resolved the issue. Thanks