What happened

For terrain, if you try to change the material, the required shader, DefaultHDTerrainMaterial.mat, along with other HDRP materials, don't show up in the menu.

How we can reproduce it

1.Create a 2019.2.0f1 3D project without HDRP
2. Create a terrain
3. Import HDRP version 6.9.0
4. Create an HDRP pipeline asset
5. Go to project settings -> graphics and drag and drop the pipeline asset into the slot
6. Select Terrain
7. Go to the settings tab
8. Go down to Basic Terrain -> Material
9. Click the circle to change the material

Expected result: every material in the project and the packages should be listed
Actual result: HDRP materials are missing
Workaround: you have to go into the package directory and find DefaultHDTerrainMaterial.mat and drag and drop it into the "material" slot. If you click the circle then, it will list all the HDRP materials.