As a workaround, and it's not documented (agree it should be) but here is code that will tell LM the device is live. Can be added to an existing groovy DataSource.
import com.santaba.agent.live.LiveHostSet
// Update the liveHostSet to tell the collector we are happy (updates Host Status)
hostId = hostProps.get("system.deviceId").toInteger()
liveHostSet = LiveHostSet.getInstance()
liveHostSet.flag(hostId)
For others: just be careful with this. Since this is designed to bypass LM's built-in dead-device detection you want to determine that the device is really still up before calling this code. But may help you code around limits with the existing dead-device methods.
This is likely also unsupported by LM, although I got the code from some of their own DataSources.