Release : 20.2
Component : PERFORMANCE MANAGEMENT INTEGRATIONS
LifeCycleState is not persisted attribute, since its value can be changed frequently. It's value stored in the iRep.
This is fixed in 21.2.2.
To make this attribute available through the open API added a new entity type devicelifestatus that has one to one relationship with the device.
To get device life status use expand operator, look at the following query:
/odata/api/devices?$expand=devicelifecycle&$select=ID,Name,devicelifecycle/State