Observational surveys have identified several giant gravitationally lensed arcs in galaxy clusters with angular sizes substantially larger than predicted by standard Lambda-CDM lensing models. These arcs are produced by the bending of light from background sources as it passes through the powerful gravitational fields of intervening massive clusters. The mismatch between observed arc sizes and model predictions suggests either that cluster mass distributions are more concentrated than assumed, or that the source redshifts are systematically different from estimates, or that the underlying cosmological framework makes incorrect predictions about mass density profiles and their evolution. The persistence of this discrepancy across multiple clusters and observational surveys indicates a systematic problem rather than random measurement error (Sharon et al. 2005; Gladders et al. 2003).