When the (built on Unreal Engine 4) appears stuck at 45% during loading, it is usually not a crash but a heavy background process. Primary Cause: Shader Compilation

The engine processes this massive workload in parallel, and until the entire batch of shaders finishes processing. Depending on your system’s hardware, this initial configuration stage can take anywhere from 15 minutes to upwards of several hours . Step 1: Verify the Mod Kit is Actually Working

[0% - 44%] -> Initializing Core Modules & Discovering Assets [45%] -> Core Shader Compilation Stage (Heavy CPU Usage) [46% - 100%] -> Initializing Viewport & Launching Project Browser

This isn’t a crash but a where the progress bar stops moving, often with the music still playing.