In the ShaderFX editor for your Stingray PBS node, if you perform an illegal operation, such as multiplying a float2 with a float3, you obtain an error Swatch Rendering not supported for this node at this time when you click the Render Swatch icon. In other words, your swatch does not compile.
Select Settings > Show Swatch Compile Errors, then click the Render Swatch icon, and inspect the errors that appear in the ShaderFX editor window.