Hi, thanks for binging this.
I have a fix here, which will be most likely be merged next week:
We have some logic for single selects where the component closes automatically when you do a selection, this logic is not present for multi-select as we expect people to choose multiple items. However, we do use few multi-select component with a maximum limit of 1, which makes it indeed slightly unexpected when you do a choice and the component looks like it expects more. 