Why does my OBJ 3D model broken animation in manual fixing?

OBJ 3D models often have broken animations during manual fixing because the OBJ format doesn’t support animation data (e.g., keyframes, skeletal rigging). OBJ is a static format—it only stores geometry (shape) and textures, not movement or rigging. So any manual animation edits (like adding a skeleton or keyframes) won’t save to the OBJ file. When you reload or export, those changes disappear, causing broken animations. To fix this, use animation-friendly formats like FBX or glTF. These formats preserve animation data, so your manual changes stay intact and don’t break.