Despite their high ionic conductivity and manufacturing advantages, sulfide-based solid-state electrolytes face challenges with initial capacity loss during full cell cycling. We use neutron computed tomography and radiography for in situ lithium-ion tracking, which sheds light on lithium distribution and migration patterns. The research examines a battery with a 7Li anode, ß-Li3PS4 (LPS) electrolyte, and LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode. Key findings reveal lithium accumulation at the LPS/NMC811 interface and in LPS pellet cracks, leading to significant initial capacity loss. The study concludes with strategies to improve cathode/sulfide interface engineering and reduce LPS pellet defects, aiming to enhance capacity retention in all solid-state batteries.