A Group Object configured with the flags C+R+T+U but without W cannot receive writes from other devices - it can only be modified locally by its own device.

Without the W (Write enable) flag, incoming Group Value Write telegrams are ignored. C, R, T and U remain active: communication is allowed, reads are supported, outgoing transmissions are possible and internal updates are processed. This combination is useful for read-only "status" objects whose value is determined locally and must not be overridden from the bus.

When in doubt about a status object that mysteriously stays stuck, list its flags first: a missing W or a missing T explains most "why is this value never updating" mysteries on the bus.