GX Works3 and the MELSEC iQ-R series do not use actual devices as automatic assignment devices of local labels.
The local labels use “label areas” in the “device/label memory”.
You do not have to worry about devices such as when using GX Works2.
Select [Navigation Window] -> [Parameter] -> [CPU Module] -> [CPU Parameter] -> [Memory/Device Setting]
-> [Device/Label Memory Area Setting] -> [Label Area] and specify the space.