Debugger doesn't display local variable

I try to debug some opencl kernel in Visual Studio 2013. After entering in kernel debugger show me local variables, but only before row with union operator (#11). Once debug go to row 11 a "Locals" window is cleared. I think this is a bug. (sorry for my english)

__kernel void randn2(float sigma, unsigned int user_k, __global float4* out)
{
	philox4x32_key_t k = {{get_global_id(0), get_global_id(1)}};
	philox4x32_ctr_t c = {{ 0, 0xf00dcafe, 0xdeadbeef, user_k }};
	float4 buf={0, 0, 0, 0};
	float2 cos2;
	union {
		philox4x32_ctr_t c;
		uint4 ui;
		float4 f;
	} u;
	u.c = philox4x32_R(7,c, k);
	u.f = convert_float4(u.ui) / UINT_MAX;