WMS UM breakdown

In JDE WMS, we have defined 2 item dimension groups in a similar way and then use similar warehouse process groups on both item categories to have only one set of rules applying to both.

The rules apply to both groups but for one group the suggestion cannot breakdown to the lower level (kg). Beside the setup in P46011, what could define if a UM can be broken down to smaller unit or not?

For reference, here's a view of our P46011 setup:

Regards
Nicolas
JDE 9.2 Release 23
TR: 9.2.7.2