Here is a sample of code :

onMove function just returns true, onStart and onFinished are empty (but I want to do something with them in the future ;) )
When the "v-model" property is here, the li tags which are created cannot be swapped.
When I remove this property, the li tags can be swapped.
Do you see the problem? Are they some "conflicts" between some properties that I am not aware of?
Is v-for and v-model are referencing the same object?
If not => jsfiddle
The solution of @VernalVessel is the good one : "The main diference is that list prop is updated by draggable component using splice method, whereas value is immutable." It's exactly what I was searching for :)
Thanks!
Most helpful comment
try this.
https://github.com/SortableJS/Vue.Draggable#list