How to deploy Extn_attributes via Page Composer?

Summary:

I have created a sandbox and enabled the Application composer to add a new field in the Projects Change Order field.

But after publishing the sandbox, It's not visible when creating a new change order:

Content (please ensure you mask any confidential information):

wanted to add a new field here:

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):