I'll explain it here:

During its initialization, the list-picker removes empty options (e.g: <option value=""></option>  it finds in the source <select>.

The main reason is that we don't want to display an empty item in the dropdown. Also, this option was considered useless since we control the selected values programmatically,

Nevertheless, it did not come in our mind that HTMLSelectElements auto-select the first option inside the list of options, even if we do not select it using the selected attribute.

Thus, we should still ignore these options, but we should not remove them, otherwise, placeholders are never shown at initialization.

This issue does not happen in multi-list-pickers.