Issue Summary:

When a  single-select custom field migrated from Connect to Forge  has an option configured with `defaultValue`, creating a new issue via the Jira Cloud REST API without explicitly providing that custom field leaves the field empty.

Steps to Reproduce

 1. Migrate a single-select custom field  from Connect to Forge
2. Add or update an option for the field using the Jira Cloud REST API for app-managed custom field options
3. Set defaultValue on one of the options
4. Create a new issue/work item using:
 

`POST /rest/api/3/issue`

5. Don't include the migrated custom field in the issue create payload
6. Fetch the created issue and inspect the migrated custom field value

Expected Results

The issue occurs when the migrated single-select custom field is populated with the configured default option.

Actual Results

The issue is created with the migrated single-select custom field left  empty 
 

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available