el-select is bound to multiple to implement multiple selection in the drop-down box. Due to the deep nesting of data, it will appear visually that the multi-selection drop-down box cannot be edited or deleted. In fact, the data has been updated, but the page has not been re-rendered, so we need to call this. The $forceUpdate() method forces the Vue instance to re-render.
Solution: Bind @change="$forceUpdate() in the el-select drop-down box component"
