All-solid-state lithium metal batteries (ASSLBs) are considered the next-generation electrochemical energy storage solution, potentially replacing conventional liquid-state lithium-ion batteries (LSLBs) due to their theoretically higher energy and power densities, as well as their enhanced safety. However, challenges such as low electrolyte ionic conductivity and dendrite formation still hinder their widespread application. While significant breakthroughs have been achieved in enhancing solid electrolyte materials, limited efforts have been dedicated to developing finite-element models that address these challenges through multi-physics couplings. This research aims to propose a mechanistic theory for predicting interface stability in ASSLBs involving the evolution of voids in Li metal electrodes during charging and discharging. A phase-field formulation is developed to allow a dynamic tracking of the evolution of the void-lithium interface, coupled with a viscoplastic description of Li deformation that captures creep effects and incorporates mass transfer. The model also accounts for the interaction between the electrode and the solid electrolyte, predicting current distributions and local current 'hot spots' that precede dendrite formation. The evolution of voids and current hot spots is successfully predicted as a function of applied pressure, material properties, and dis/charge history. Key experimental observations are captured, including current density distribution in electrolyte and void morphology, sensitivity to applied current, the role of pressure in enhancing electrolyte-electrolyte contact, and the dominant role of creep on void diffusion. The results demonstrated the capability of the model to correctly predict the dynamic evolution of the interface morphology during battery cycles. However, through quantitative analysis, its limitations in high-pressure-related simulation are acknowledged. Despite these challenges, this model constitutes a novel contribution to this research field and offers insightful understandings for researchers through qualitative analysis.