Thanks so much for the messages!
I did have the "Offline Access" enabled (not realizing it) and so I turned that off and did what you said, and it freed up about 3.6 GB of space on my phone. I know it freed up that much space because I was able to download my latest iOS update and it wouldn't let me do it (for lack of that much space) before doing this.
But interestingly, it still says I have the same amount (as before I did the above) tied up in Documents and Data (see photo).
