I ran into the same issue. It turns out there is a defect when using localhost. Justin was able to figure out a workaround until it gets corrected.
In my logshark.config file, I needed to change localhost to my actual machine name under PostgresConnection.
In the Postgres pg_hba.conf file, I needed to add two host records to allow IPV4 and IPV6 connections as described in #5 under Install and Configure PostgreSQL in the Logshark docs: Install and Configure PostgreSQL .
After modifying the pg_hba.conf file, I needed to restart the PostgreSQL service under Services on my machine.
Similar to running Logshark from a different machine than where the PostgreSQL db is installed.