Why does moving a Device from one Data Collector to an other one in the same IP domain manually fail?
When moving a Device from one Data Collector to an other one, the target Data Collector will try to ICMP Ping and SNMP Poll the Device.
Only if the response is successful it will move the device.
You can force a move by stopping the Services on the source Data Collector and performing a re-balance with the target Data collector.
This will force all devices from the offline Data Collector to the target Data Collector.