vue multiselect array is not updated
Use @select (for select a new element from array) and @remove (for delete element from array)
Example: <multiselect @select="selectionChange" @remove="removeElement" required>
In vue methods add:
this.$forceUpdate(); will update the state
 methods: {
    removeElement() {
      this.$forceUpdate();
    },
    selectionChange() {
      this.$forceUpdate();
    },
 }