For a couple labs, they say to:
"Ensure full IPv4 reachability to Loopback0 prefixes from all internal devices, and to all prefixes learned from AS 54 from R1 - R8 when sourcing traffic from Loopback0 interfaces."
For R10, this is fine as its lo is advertised into BGP. That being said, R9's loopback0 isn't advertised into BGP (using the provided configuration set). If I source lo112-119 the pings work fine.
Thanks,
Kyle