If the discovery parameters of the agent-less machine are changed such as serial number, then we need to perform reset discovery key under Settings > Node Operations page, and then rediscover the device. Post that need to verify the inventory status after scheduled cycle or by posting on-demand.
If there is no change in discovery parameters, rediscovery is not required. See the data collection failure reason and take corrective action. Reasons could be WMI/SNMP connectivity failure, Credential change, port change, network issues, device access control,etc.