Visualizing Custom Stencil Buffer returns incorrect results when an Actor with Render CustomDepth Pass enabled is visible

This is a regression tested in //UE4/Release-4.27 CL 18319896

Visualizing Custom Stencil Buffer returns incorrect results when an Actor with Render CustomDepth Pass enabled is visible.

1. Create a  Third person Template project
2. Place the 'ThirdPersonCharacter' in the scene so that's its visible
3. Enable 'Render CustomDepth Pass' on the 'ThirdPersonCharacter'
4. In the Viewport set View Mode to Buffer Visualization > Custom Stencil

Expected Results:
Character and Scene are render black

Actual Results:
When ever the character is visible RBGA artifacts are present