Identifier Assignments form: Selecting the format of “Default (#)” should place the correct format in the field

On the Identifier Assignments form (e.g. /registry/co_identifier_assignments/add/co:2), selecting the Format of “Default (#)” does not place the format string in the input field like the other selections do (see screenshots). When "Default (#)" is selected, the format string "(#)" should be placed in the field.

Note: technically a blank value and (#) are the same thing, but the behavior should be consistent for each selection.