Here are steps to enable new fields for Configurations and Contacts, including custom ones, and bring them to your report
1. Settings - Integrations - Your PSA Integration (f. e. Autotask) - Configurations or Contacts
Select additional fields in "Fields to download" area, then click "Save mapping":
2. Settings - Integrations - Your PSA Integration (f. e. Autotask) - Run Force Sync:
3. Make sure sync has been finished (Settings - Integrations - Your PSA Integration - Logs):
4. Make New version of your Report (to bring new columns with data):
5. Click "Columns" option under "Assets" / "Contacts" Tab in report and setup new fields for Build / Display / Presentation mode: