Default value (DefaultValue) on specification is accepted for all specification types, except Checkbox, Combo, or Radio when creating/editing a specification through Admin, but it is accepted when creating a specification via API.

Simulation

1. Execute the API route Create specification with the field DefaultValue filled and the field FieldTypeId filled with the values 5 (Combo), 6 (Radio), 7 (Checkbox).
2. The response body will show the new specification payload, with the DefaultValue filled.

Workaround

As it is not possible to edit the DefaultValue field via API because the [KI] DefaultValue property doesn't update on specification API, execute the steps hereafter to change the DefaultValue field value:

1. On Admin, edit the specification by changing the field type to 1 (Text), leaving the DefaultValue field empty, and save the changes.
2. Then, edit the specification again by changing back the previous field type, and save it.