I am option + command dragging a folder of images into a database. When I synchronize the folder, it and the images are removed from the database. Obviously there is external representation for both the folder and the image. What is happening here? This is really throwing me for a loop! 
Hi, Jerry. As you are Index-capturing the folder and images, they must remain in the Finder at the position expected by the database. Otherwise, they will disappear from the database content when the Synchronize command is invoked.
Please select one of your Indexed groups and open DT Pro’s Info panel. Check the Path for that folder. Then see if it is at that position in the Finder.
If that external folder has been moved in such a way as to break the Path (or was deleted), its representation in the database will be removed when the Synchronize command is invoked.