Troubleshooting
The preview does not show the model in the same place as the game
Make sure Model is the same prefab root or GameObject used by the Attach Prop instruction. Using a child object or the raw FBX instead can give a different result.
The Free Hand IK preview looks wrong
Use a Preview Animation that matches the weapon pose in the Sight asset, usually an aim animation. A relaxed or unrelated pose can place the hand far from the model even when the Sight values are correct.
The tool cannot retarget or save an entry
The selected Handle entry must use fixed Vector3 Position and Euler Rotation values. Dynamic Handle values cannot be moved between character rigs reliably, so Handle Editor leaves them unchanged and reports an error.