Here is our Docker file and docker-entrypoint.sh. I hope this helps. I contributed some of this but not all of it, so I'm not sure why the default ENTRYPOINT is not working for you.
FROM metabase/metabase-enterprise:v1.46.1
COPY docker-entrypoint.sh /app/
RUN ["chmod", "+x", "/app/docker-entrypoint.sh"]
ENTRYPOINT [ "/app/docker-entrypoint.sh" ]
#!/usr/bin/env bash
if [ "$PORT" ]; then
export MB_JETTY_PORT="$PORT"
fi
/app/run_metabase.sh