I have a huge catalog 400,000 + images but they are all jpegs on the average 2500pix on the long edge. The problem is when I try to synchronize a particular folder which has 18,000 images with sub folders, it comes up with 300 images to sync but then its starts importing images that are not part of that folder about 1,200 of them. The images look like sample images from apps like Filemaker and photoshop most are small tiffs/png. They don't exist in the folder I'm trying to synchronize. Any idea how its linking to random files that are in my apps folder? I tried renaming and duplicating that folder to a different location on the HD but still happening. I upgraded to LR CC, same problem
Please post a screen shot of the LR window with the folder you are selecting to sync.
Sounds like you have the Top Level DRIVE selected and not a folder.