Thanks, Daphne but, it looks like it was "operator error"rather than a problem with DropBox. I keep my LightRoom photo library, about 65,000 images) on an external USB drive and move it around to my different computers as necessary. I have the Win10 system Dropbox setup so that it will treat it as a camera/memory card and will upload the pictures to DropBox's camera roll. I think I have it setup so the pics are ony stored in the cloud. I did they bychanging the CameralRoll folder Smart Sync to "online ony" When I pugged the external drive back into the Win10 machine it properly identifed 61 pics as being new or changed. Apparently it firstimports them to the computer's main hard disk and then does the upload and once successfully uploaded changes the icon to a cloud. I saw the new green checkmark icons on my main hard disk and thought DropBox was failing, it wasn't. I was. So, I once again marked the CameraRoll folder as "Online only". This caused DropBox to reindex everything and while it was reindexing it reported an extra 500+ GB of drive C as being used. Hence, my post. After I posted I did a chat with DropBox Support and Everett helped me figure it out.
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