MaterialExpressionSubtract doesn't compile in plugins

Adding the following code to a plugin source file prevents the associated project from compiling in visual studio whereas this code will compile successfully inside of a class added directly to the project.

#include "Runtime/Engine/Classes/Materials/MaterialExpressionSubtract.h"
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.
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UMaterialExpressionSubtract* Multi;

This was tested with both UMaterialExpressionMultiply and UMaterialExpressionSubtract

1. Open UE4 Editor
2. Open Edit->Plugins->New Plugin
3. Make a new plugin based on Toolbar Button (MyPlugin) (restart the editor as prompted)
4. Open MyPlugin.h in Visual studio and add the two lines of code shown in the description
5. Compile the code

Result:
Compile fails to complete

Repro Rate:
2/2