Quintin - The Toolset (and all of SolarWinds products) require a community string (cannot be blank) when sending SNMP Packets.
Do you actually have any devices that will actually respond to an empty community string?
So I am being told by a security vendor. I thought the problem was that it used a default community string, but with the default string disabled I tested and it no longer responded so I thought it was fixed. WRONG! it now responds to a blank string according them. I was sent an SNMP walk to prove it. But I wanted to confirm for myself.