Dynamic mechanical analysis was performed in two metallic glasses that show markedly distinct beta relaxation features. The confined flow defects of free-volume zones and the inelastic deformation behavior result into a significant mechanical hysteresis loop in dynamic cyclic loadings, which is described with a viscoelastic model. Annealing below the glass transition temperature T-g decreases the concentration of free-volume zones. The understanding of the inelastic deformation, which is related to free-volume zones, is critical and may provide a new avenue into the mechanical properties' improvement of high entropy metallic glasses. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.