I am working with the latest version of ArcGIS Pro. I have been using zipped contour files from MassGIS. I am able to download them and unzip them. However, they simply don't show up in the "add data" lists of files. They are in my windows explorer files, so I know I have them. I have tried unzipping them from the download folder, without any luck. I tried copying them to another folder on my computer, and that worked twice, but no longer. Any ideas??