Select Box component does not work with a single value

When using the Select Box component from the Hippo Theme [1], the value of the assigned model to it is not correct.

It is also not possible to select the last item from the dropdown.

Above only counts for a Select Box with a single value. A Select Box which allows multiple selected values works as expected.

[1] http://onehippo.github.io/hippo-theme-demo/