Discovery is not adding new Agent nodes so if there is an agent node in the results it should be one that already exists in Orion. Do you have some nodes that have polling IP set to 255.255.255.255?
Logs from discovery should tell us more so if you want to find out more I suggest you to open a support case and provide Orion Diagnostics (c:\Program Files (x86)\SolarWinds\Orion\SolarwindsDiagnostics.exe, click "Start and save diagnostics").
Post a case number here once you have it.
Discovery is not adding new Agent nodes so if there is an agent node in the results it’s one that already exists in Orion. The only difference for agent nodes should be that they are not deduplicated, we allow same IP multiple times if it’s agent.
Following up it appears that the IP address of 255.255.255.255 is displayed when there's an absence of an IP address in discovery. This occurs because we allow overlapping IP addresses to report to the same polling engine with the Agent. This purely cosmetic. The 'real' IP address of the node should appear anywhere else outside of discovery.
I have not started a case yet but did confirm that the discovery tables for each batch ID are populated with the 255.255.255.255 IP while everywhere else the agent is reporting polling IP.
I agree it might be cosmetic but it also seems incorrect in that the non-overlapping nor nat IP should have populated the discovery jobs.
I only ask as I'm populating device details pages with the discovery data so we know when and how things have been added.