The Application icons are not showing up in the Library, and/or the Tags are not showing.
This can happen after Snagit has been reset, or reinstalled.
Application icons missing
To get the Application icons to reappear in the Library, simply take a single capture of the application where the icon is missing. In the example below, the Console.app icon is missing. After taking a single capture of the Console.app, the icon reappears.
To get the tags to reappear, simply add the missing tag to any capture, and the rest of that tag will appear. In the example below, the "test" tag is missing. After adding "test" as a tag to a new capture, the tag now appears in the Library and displays all of the images using that tag.