We have the following issues that I hope to draw some assistance on regarding the SolarWinds Agent.
1) The agent is installed and the Node appears to be monitored by SW Orion, but the Application Connection will not appear.
There are no logs that support failure of any kind on the server(s), and uninstalling the agent and reinstalling does not fix the issue.
2) The agent is not present in the Services nor Add or Remove, but there's a folder in the C:\Program Files (x86)\ called SolarWinds (empty).
If you try to install the agent (v2.1.666.0) via Orion (Manage Agents) or via MSI, the MSI install fails to install referencing version 1.8.551.0 (with the folder present or not).
The only error that I've found so far has been in the Manage Agents, which states: "unexpected error occurred during the Agent deployment and installation"