Answer:
Please check whether you have selected sets of members for the design in General Data: The module extension RF‑/STEEL Warping Torsion can only be used for the design of sets of members, not for individual members.
Please check whether you have selected sets of members for the design in General Data: The module extension RF‑/STEEL Warping Torsion can only be used for the design of sets of members, not for individual members.