Enabling Shader compilation via XGE for 4.18 Editor downloaded from Launcher doesn't work, prevents shaders from compiling at all, editor from loading in some cases

If you enable Shader compilation via XGE by setting r.XGEShaderCompile = 1 in ConsoleVariables.ini in 4.18 Editor downloaded from Launcher, it prevents shaders from compiling at all, and as a result sometimes the editor will never finish loading because it's waiting on shaders to compile. Additionally, launch on/cooking/packaging is not possible.

Licensee reports this happens when they make a build with InstalledBuild.xml themselves as well.

This issue does NOT reproduce in Release-4.18, only in a build created with BuildGraph and InstalledBuild.xml (so it does reproduce in 4.18 downloaded from the Epic Games Launcher)

From Luke Thatcher: “This might break if the InstalledBuild script does not include XGEControlWorker.exe in the launcher build. This was a new .exe (actually just an on-disk copy of ShaderCompileWorker.exe), which is required for the new XGE interception system to function.”

1. Uncomment this line in Engine/Config/ConsoleVariables.ini (remove semicolon at beginning):

   ; Uncomment to enable XGE shader compilation.
   ;r.XGEShaderCompile = 1
   

2. Create a new project and hit Ctrl+Shift+. to recompile shaders, or create a new simple material or change an existing one and try to recompile.