<oj-c-select-multiple> is not selecting multiple

Summary:

I'm looking at the cookbook for <oj-c-select-multiple> examples and when I click an option it acts like a single select ( ). If I click CTRL on my keyboard and then select then it selects multiple. Why is this? How can I select many without having to press CTRL.
I also noticed that on mobile it does work but not on desktop.

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