I'm using Unity. Why do I get a warning when enabling "Multipack"?

Unity's sprite sheet import API does not support Multipack, meaning each sprite sheet is imported independently. If a sprite that’s already used in Unity moves to a different sheet, it will result in a broken sprite reference in your Unity project!

Auto Multipack automatically distributes sprites across multiple sheets, trying to optimize space. Each time you add/remove/change a sprite, the packer layout changes, and other existing sprites might be shifted between sheets, causing broken sprite references. This is why a warning appears when enabling it.

Manual Multipack lets you assign sprites to specific sheets, preventing automatic movement. This is the recommended mode for Unity users. If you manually move a sprite to another sheet, be sure to update all related references in your Unity project!