HISM flickering when any character is visible

On an NVIDIA GPU, Instanced Static Meshes can flicker when a Groom card or mesh LOD is visible.

This appears related to an issue rendering the ISM into the Scene Depth. At the end of the Prepass, the depth is correct, and the ISM is visible. In the very next pass to write to the depth (In this case, DitherStencilClear), the last draw call to the depth appears to be reverted, and the pixels restored to their former state. When the basepass comes, if the objects behind the ISM render after, they will override the GBuffer pixels, due to the depth test passing.

This issue does not appear on AMD GPUs.

Also tested on //UE5/Release-5.6, CL: 45232827

1. On a workstation with an NVIDIA GPU, (Driver version 591.74 - latest at time of writing), download the Licensee's test project and open (see addl info URL)
2. Open the map "/Game/TestMap"
3. Look at the instanced cubes and the character
4. Move backwards until the cubes flicker
5. Observe the flickering