How to reproduce:
1. Open the user's attached "1409175_My project" project
2. Open the "SimplePlacerScene" Scene
3. Select the "Placer" Prefab in the Hierarchy
4. Observe the ReorderableList under the "Item Placer" Component in the Inspector

Expected result: UIToolkit Inspector matches the IMGUI one: ReorderableList Header text is visible
Actual result: ReorderableList Header doesn't exist. Instead, the List size field is present

Reproducible with: 2022.2.0a9
Couldn't test with: 2019.4.37f1, 2020.3.33f1, 2021.2.19f1, 2022.1.0b15 (UIToolkit Inspector isn't featured)

Note: Expected view of the Inspector can be observed if the "Use IMGUI Default Inspector" is toggled on in the "Project Settings -> Editor" settings