Unexpected behaviour when not removing from data array

Hi! Im not very familiar with sortablejs

const baseTasks : Array<{ id: Task['id'] }> = [ {id: '1'}, {id: '2'}, {id: '3'} ]
const taskList : Ref<Array<{id: Task['id'], removed?: boolean}>> = ref([]);

Im using the following add/remove handlers without removing the task from the list

function listOnAdd(event: SortableEvent): void {    
    const taskId = event.item.getAttribute('task-id');
    if (typeof taskId !== 'string') throw new Error('Invalid Task Id!');
    
    event.item.remove();
    taskList.value.push({id: taskId});
}

function listOnRemove(event: SortableEvent): void {
    const taskId = event.item.getAttribute('task-id');
    if (typeof taskId !== 'string') throw new Error('Invalid Task Id!');
    
    const taskIndex = taskList.value.findIndex(i => i.id === taskId);
    if (taskIndex === -1) throw new Error('Task not found!');
    
    taskList.value[taskIndex] = {id: taskId, removed: true}; // only mark them as 'removed'
    // taskList.value.splice(taskIndex, 1);
}

function listOnReset() {
    taskList.value = [...baseTasks];
}

 <button @click="listOnReset">reset</button>

 <Sortable
    ref="sortableElement"
    class="task-list"
    :list="taskList"
    item-key="id"
    :options="options"
    @add=     "listOnAdd"
    @remove=  "listOnRemove"
  >
    <template #item="{element}">
      <Task :task-id="element.id"/>
    </template>
  </Sortable>

The elements that are moved between categories, when reset, dont seem to be added again.
https://stackblitz.com/edit/recursive-template-refs-5ip6ao?file=src%2Fcomponents%2FTaskList.vue

Is this correct behaviour? I'm a bit surprised that the elements are not behaving as a clone list

Start with the linked StackBlitz reproduction and inspect the Vue component using the Sortable wrapper. Trace the @add and @remove handlers, the taskList updates, and listOnReset behavior. Done means establishing whether reset should restore moved elements when removed items are only marked rather than spliced, and documenting or correcting the observed behavior.