When You use dropdown with static choices and you set up a default value, placeholder value is not showing up keeping dropdown value box completly clean (backend reads default value as it should).
I believe when you setup a default value there should be option to populate this default value to placeholder box.
Also when you let input box be empty in a dropdown you get an extra empty row.
Short fix could be about making placeholder as label on empty (picked on load) row.
When default value is set it should be populated as currently picked value in dropdown box.