once edited, fields cannot be set back to empty values

Fields (like organisation's name, street address, but also drop-downs like state and country) cannot be set back to empty values.

The steps:
Create an organisation with nickname, street address, state and/or country.
Edit it and clear nickname and/or select the first option from the drop-downs.

Current result:
The fields don't get cleared.

Expected result:
The fields get cleared.