Using TerrainPaintUtility in game works in preview but not build

I'm experimenting with modifying terrain in-game with TerrainPaintUtility in the Experimental.TerrainAPI.

Basically I'm calling TerrainPaintUtility.BeginPaintHeightmap, blit the modification into the paintContext's destinationRenderTexture and then call TerrainPaintUtility.EndPaintHeightmap.

This works great in preview mode but doesn't work in an actual build.
I've tried calling SyncHeightmap on the corresponding terrainData afterwards but that didn't do the trick.

What additional steps are required to get this working in the game build, or are these methods only intended for use in the editor?

Thanks!

 

Chris, Thank you for your answer. I've been trying with 2019.1.11 and 2019.1.12 on macOS. In both versions it works in game preview but not in the standalone build. I've converted the project to 2019.3.0a10 but that didn't help either.
The Builtin Shaders package for 2019.3.0a10 doesn't contain a TerrainHeightBlitCopy.shader (neither do the packages for 2019.1.11/12) so I couldn't try what you suggested.
I've also tried with 2018.4.5f1. That doesn't seem to work either.

 

I'm having this issue, too. I'm using Unity 2018.4.25f1 (LTS). The TerrainPaintUtility works in the editor's game preview, but in a standalone build (Windows 10) the call to TerrainPaintUtility.GetBuiltinPaintMaterial() returns null. I presume that's because the shader is that Chris mentioned is stripped from the build. But I'm unable to find it in order to add it to the project's preloaded assets list.

UPDATE: I found the correct shaders. To be more clear about where to get these shaders: go to the Unity Download Archive web page, find your version of Unity and change the drop-down selector from "Downloads (WIN)" to "Built in shaders". Inside the ZIP file that is downloaded there is a folder named "DefaultResourcesExtra\TerrainShaders\Utils". I copied those shaders into a "Resources" folder in my Unity project. Then after rebuilding the standalone game, everything works as intended.