Uptodate conflicting having 1+ peers in BGP

In Lithium I can add one BGP peer successfully

however when I add a second peer things go wrong.

Both peers are visible in config:modules.

both BGP sessions are up.

but getting the RIBs via /bgp-rib:bgp-rib/rib/example-bgp-rib/ fails (HTTP ERROR 500). this seems to happen immediately - i.e. before any routes are actually received from the peer.

I can get LocRIB ok.

Attempting to get the first peer (via /bgp-rib:bgp-rib/rib/example-bgp-rib/peer/bgp:%2F%2F172.23.29.116) also gives me HTTP error 500.

Attempting to get the second peer gives me a 404.

The IPv4 topology looks correct.

logs attached.