According to your article, macOS Catalina is not listed as a supported OS. I've installed the agent on two Catalina test machines. The first Catalina machine (configured in Jamf MDM) doesn't report at all. This might be a security setting blocking reporting; I need to investigate further.
The second Catalina machine reported, but its data attached itself to different device -- one that was used to migrate a user directory (using Apple's Migration Assistant) to the machine with the agent installed.
Anyone successfully using the Discover Agent on Catalina machines?