The product will start showing the data from your environment after 2 hours of data collection
Also, please follow the instructions in this guide: https://www.vmware.com/pdf/vrni/vrealize-network-insight-30-user-guide.pdf
In here you will find all the information you need to set up Network Insight correctly.
you can check if the host send flow to proxy port UDP2055,and then check if receive the flow in the proxy.
You can check firewall rules if it deny UDP2055 between esxi host and proxy.
Did you ever get this resolved?