Terrain material asset is not getting generated when it's created from Terrain Settings in the preset of Terrain, Refer attached video.

Steps to repro:
1. Create a new project.
2. Hierarchy > Create > 3D Object > Terrain
3. Create Preset of Terrain
4. Project > Terrain > Inspector > Activate this inspector
5. Terrain Settings > Basic Terrain > Material > Create a New Material

Actual Result:
Terrain material asset not getting generated when its created from Terrain preset

Expected Result:
Terrain Material asset is created gracefully

Reproducible in:
2021.1.0a5, 2021.1.0a4

Working fine in:
2021.1.0a3, 2020.2.0b11

Environment:
Occurring on Windows10 and macOS 10.15