Channel Mask Parameter does not correctly pull through the Alpha channel from

The ChannelMaskParameter node in the Material Graph works in most cases, but unusually does not work when extracting the value of the Alpha channel only for Vertex Color input data.

• Create a material that lerps between two colours, with the alpha based on the alpha channel of a Vertex Color node
• Create one implementation that uses the alpha channel directly from the Vertex Colour node, and another that uses the ChannelMaskParameter node set to the Alpha channel to extract that same value
• Apply the material to an object in a level and use the vertex color painting tool to paint with the alpha channel
• Observe that the material implementation using alpha directly from the Vertex Color node works as expected, but it does not work with the ChannelMaskParameter implementation
• For completeness, also try drawing with other channels, e.g. Red, and alter both material implementations
• Observe that the ChannelMaskParameter successfully extracts other channels, and that the issue is limited to the Alpha channel