Hello,
The answer can be found in the documentation:
********** On MX Series 3D Universal Edge Routers containing both DPC and MPC FPCs, chained composite next hops are disabled by default. To enable chained composite next hops on the MX240, MX480, and MX960, the chassis must be configured to use the enhanced-ip option in network services mode.
https://www.juniper.net/documentation/en_US/junos/topics/concept/network-services-mode-overview.html
!!!!!! Enhanced IP Network Services mode (upon boot) Only MPCs, MS-MPCs, and MS-DPCs are powered on.
Note: Only Multiservices DPCs (MS-DPCs) and MS-MPCs are powered on with the enhanced network services mode options.
!!!!!!!!! No other DPCs function with the enhanced network services mode options.