This is the only screenshot I see in the KB that shows the configuration piece, you will want to launch the SolarWinds Log and Event Manager MSSQL Auditor Configuration tool:
It has an error there as well that you can disregard, but this was the only screenshot I saw in the KB. The tool includes instructions for targeting a remote server.
The full instructions are here and they're mostly the same for a local and remote server:
Configure MSSQL Auditor on a LEM Agent - SolarWinds Worldwide, LLC. Help and Support
One other thing that came to mind from what you were describing, though you said that it tested fine previously, I figured I would include just in case: