You want to enable the resourcing attributes in the New UI / UX (User Experience).
The API attribute ID is set for the attributes. However, the resource attributes do not appear in the Staffing plan or Resources (Teams). You only see these fields:
You have been granted all the new UI-related access to your profile. Is there anything related to permissions missing or is this a limitation?
Release : All Supported
Component : CLARITY STUDIO
This is working by design. These sections are not configurable. The one option in the Modern UX would be to use the Staffing grid where you are able to add additional columns to both the grid and Details flyout.
For the steps on how to submit an idea, see: Enhancement Requests for Clarity