There was a bug in 4.14, if you find PostProcessDOF.cpp and look for:
OutEnvironment.SetDefine(TEXT(“FORWARD_SHADING”), IsFeatureLevelSupported(Platform, ERHIFeatureLevel::SM4) ? 0u : 1u);
and change it to:
OutEnvironment.SetDefine(TEXT(“MOBILE_SHADING”), IsFeatureLevelSupported(Platform, ERHIFeatureLevel::SM4) ? 0u : 1u);
You’ll probably need to modify shaderversion.usf to trigger a shader rebuild too.