Reproduction steps:
1. Open the attached “BugRepro” project
2. In the Project window, select the “Assets/Ghost“ Asset
3. In the Inspector window, select the Rig tab and press “Configure…”
4. Observe the opened Inspector window of the Avatar

Expected result: Avatar Mapping tab is visible
Actual result: The Inspector window is empty

Reproducible with: 2022.3.25f1, 2022.3.35f1, 6000.6f1
Not reproducible with: 2021.3.40f1, 2022.3.24f1, 6000.0.8f1
Fixed in: 6000.0.7f1

Reproducible on: Windows 11
Not reproducible on: No other environments tested

Workaround: After the Inspector window is open in the Avatar Configuration mode, reset the layout to default (Window > Layouts > Default)