Can't use screen position node in UI custom shader

Steps to reproduce:

1. Create a new UITK Shader Graph
2. Add a Render Type Branch node
3. Add a Default Texture node and override the Texture input
4. For its UV input, use Screen Position

Actual results: 

Shader should compile

Expected results: 

Shader is pink with the following error:

Shader error in 'Shader Graphs/CustomShader': invalid subscript 'NDCPosition' at Assets/CustomShader.shadergraph(268) (on d3d11)