If an asset shows the IP Location as undefined, it usually indicates that the asset does not belong to an IP Location as configured under the Configuration\Asset Groups tab of the Lansweeper web console.
Setting up an IP Range Scanning target will not automatically group assets in an IP Location. You will also have to configure a matching IP Range under the Configuration\Asset Groups tab. You can find more info here: https://www.lansweeper.com/knowledgebase/grouping-assets/