Vue - CSelect - How to manually set the index?

I have a button that is supposed to switch between two static options in a CSelect.

  :options="[
    { value: 0, label: 'Option1' },
    { value: 1, label: 'Option2' }
  ]"

I tried using :value.sync=“myvalue”

When I set myvalue to 0, the dropdown resets back to index 0, but if I set it to 1 nothing happens.

How would I go about manually setting the selected index of CSelect?