"Channel Remapping" foldout in the Terrain Layer Inspector does not open when clicked on its title

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. In the Project window, right-click and select Create > Terrain Layer
3. Select the new Terrain Layer asset
4. In the Inspector, assign any texture to the the Mask Map
5. Click on the "Channel Remapping" foldout's title
6. Observe the Inspector window

Actual results: The foldout does not open/expand

Expected results: The foldout should open/expand

Reproducible with versions: 6000.0.0f1, 6000.0.80f1, 6000.3.21f1, 6000.5.6f1, 6000.6.0b6, 6000.7.0a3

Tested on (OS): MacOS Silicon Tahoe 26.5.1, Windows 11