How to focus on input after power-select-multiple is rendered?

I want to be able to search right after the webpage is rendered, instead of click on the search box then start typing. However when I trying to mimic focusInput in original source code, it doesn't work.

It could be reproduced by visit https://ember-power-select.com/docs/multiple-selection and run document.querySelector('.ember-power-select-trigger-multiple-input').focus() which is focus on an input tag.

I expected to see something like this

, but actually nothing happened.

I also tried to .click() on all parent html elements of that input, but nothing happened

Any help?