Check chain and routing-graph readiness separately in LND
A replacement LND instance can answer RPC before it considers both its Bitcoin backend and public routing graph synchronized. Record both signals when deciding whether to route test traffic.
Read the two sync flags
Run lncli against the intended instance. Verify its public key and network first, since a successful query to a different node can also produce plausible heights.
lncli getinfo | jq '{identity_pubkey, chains, block_height, synced_to_chain, synced_to_graph}'
Interpret mixed readiness
If synced_to_chain is true while synced_to_graph is false, chain synchronization has caught up according to the daemon while gossip synchronization is still incomplete. Sample again and inspect peers if it persists. Even when both flags are true, a particular payment still requires usable local channels and a viable route.