Jaeger UI not showing any spans with vstart.sh --jaeger

Hi, As titled, when I trying to use the Jaeger tracing as shown in this blog post with the latest ceph repo on GitHub. https://ceph.com/en/news/blog/2021/distributed-tracing-in-ceph-using-jaeger/ I can access the Jaeger UI, but it seems like the agent is not sending anything to the collector. I already cmake with WITH_JEAGER, is the anything I missed? Thanks, Andy