Numerous conductor designs for pulsed magnets based on High Temperature Superconductors (HTS), featuring stacks of tapes are currently being proposed. A major contribution to the AC losses is expected to be given by hysteresis losses. Several numerical models have been developed for the computation of hysteresis losses, however the lack of experimental data in conditions relevant for the coil operation did not allow extensive validation of those models. Here, we present the AC loss tests performed on HTS conductor with transport current in conditions of partial or full field penetration. After the validation of a numerical model on those data, we analyze the losses expected during the operation of the EU DEMO CS coil, assessing possible analytical formulations for the calculation of hysteresis losses in DEMO-relevant conditions.