Shane,
If sFlowTrend is showing 0.0.0.0 as an agent, then you will have a switch using this address as the agent. Some vendors default to this address, which is not very useful. Can you check this on your switches, and configure the agent address there?
If sFlowTrend still isn't showing data, then one other thing to confirm is that a host firewall isn't blocking udp:6343. The Windows firewall needs to be configured as Administrator to allow it, since the service runs as Administrator. Also, wireshark inserts itself before the firewall, so that's not a good indication that things are ok. It's always worth trying temporarily disabling the firewall to test if this is the problem.
Regards,
Stuart