I'm trying to run a shuttle following the usage guide in https://github.com/farcasterxyz/hub-monorepo/tree/main/packages/shuttle, but failed to perform reconciliation/backfill task. 

The process looks like hanging there after printing the log "Starting worker connecting to: postgres://shuttle ..... "

The connections to database, redis and hub should be ok because syncing messages from the event stream works fine.

Can anyone tell me how to resolve this issue?

Try checking the PostgreSQL connection settings in your shuttle config file to ensure they match the ones in your hub-monorepo. Also, verify that the database has the necessary tables and schema set up.