Unable to get all Custom Fields from Project/Folder via API

Hey!

I’m trying to get all custom fields that belong to a project/folder via API.

Here is what I’m seeing:

• customFields only returns fields with values (expected).

• customColumnIds returns some custom field IDs, but not all fields that are visible in the Wrike UI for that project/folder.

My question is:

What are the exact rules for a custom field to appear in customColumnIds?
Some fields visible in the UI are never included in the API response.

My goal is simply to retrieve the complete list of custom fields configured for a project/folder, even if they have no values yet.

Is there a recommended or supported way to achieve this?

Thanks!