When processing UL RRC messages from PDCP, the DU association ID (assoc_id) was not being propagated to RRC, resulting in assoc_id being 0 in rrc_gNB_decode_dcch. Fix by setting originInstance in the ITTI message header to the stored du_assoc_id from ue_data when PDCP creates the F1AP_UL_RRC_MESSAGE.