Sampling 3D Textures on apple Silicon

I create a 3D texture with size 32x32x64 :

Then I write this RWTexture with a compute shader, threadsPerThreadgroup is {32,32,32}

The interesting part is that when I only write the 32 slices and then sample it in a pixel shader, the sampling result is always 0.0.

Only when I fill all the 64 slices, the sampling get what I expected.

//Fill the first 32 slices, uint3 pixelIndex = threadIdWithinDispatch; Vol[pixelIndex ] = somedata;

//Fill the last 32 slices pixelIndex.z += 32; Vol[pixelIndex ] = somedata;