Joe and I confirmed that our path to 140.221.11.45 at Argonne comes over I2.
We used the Internet2 router proxy
http://routerproxy.grnoc.iu.edu/internet2/ to look at the multicast routes on I2's routers. Our I2 router (SALT) didn't know those groups, and neither did Chicago (CHIC), where Argonne connects.
It looks like something is unhappy at Argonne or between them and I2. Joe talked to Jimmy and he will let the Argonne folks know what we've found.