I think I just solved my own problem. In order to see all the keywords in the "KEYWORDS" panel, I just have to select all the images once. Then any keywords associated with those images will show up in the panel.
Curious as to why this question was posted in the Adobe Drive forums. Are you also using Adobe Drive in your workflow?
With regard to Bridge question...might also be helpful to know that you can export a keyword collection by using the "Export" function in the flyout menu of the Keywords panel. You could export all keywords to a txt file and then import it on another machine.