How to reproduce:
1. Create a new 3D project
2. Add Terrain and a Cube to the Scene
3. In the Terrain Settings in the Inspector, enable “Draw Instanced”
4. Enter the Scene View and enable Debug Draw Mode
5. Observe the result

Expected result: The Terrain remains visible
Actual result: The Terrain disappears

Reproducible with: 2023.3.0a6, 6000.0.51f1, 6000.1.7f1, 6000.2.0b5
Not reproducible with: 2021.3.51f1, 2022.3.63f1, 2023.3.0a5

Reproduced on: Windows 11
Not reproduced on: No other environment tested

Notes:
- Restarting the project in the regressed version (2023.3.0a6) fixes the issue
- Debug Draw mode can be turned on in 2022.3.63f1 and later through the Draw Mode dropdown menu and selecting “Contributors / Receivers”