try this
this.$nextTick(()=>{ this.value = "value6"; })

I have the same problem. It seems to only happen when the focus is on the Select Box.

you should not watch value, because will lead your code perform twice, you can console log like what i done,and you can find that it console two times which is not necessary.
instead watch change event, update the options in this function . do not put the options change code put in setTimeout,that will lead element not notice value change.
here is the code.
https://codepen.io/littledevil7/pen/jOWrzra?editors=1011

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