When creating a new topic, getFieldValuesFromQuery is used to populate the form values. Because of issues that occur when an undefined value is used, it is told to initialise undefined values to ''. When the form is rendered for edit, the field is assumed to have a value (the empty string) so the field default is not applied.
Because we want the empty string to be a valid value for form fields, we need to change the call to getFieldValuesFromQuery so that it doesn't set default values for fields when a new topic is being created.
CC