Greg,
Thanks for the problem report and picture. I just did a check of a River4 install I have running on Heroku, and I was able to see the River.io console app save a change to one of my lists saved on Amazon S3, so it appears to me that the River4 console app is working.
Can you give some more information about your setup?
1. Running River4 on local filesystem, Heroku, or some other platform?
2. Can you edit the OPML manually (checking for read-only setting on the file)?
3. Did you have the OPML file open when you tried to make a change?
Andy Sylvester