Construction script in parent blueprint cannot call function in child blueprint

Construction script in parent blueprint cannot call function in child blueprint when the editor first loads. Once the parent BP is compiled it acts as expected.

Regression? (Yes), issue (does not) occur on 4.10.4

1. Download, unzip, open attached project
2. Open "A"
3. Compile blueprint
4. Save, close, restart project

Results

Asset in editor is a grey sphere with no cube over it.

Expected

Asset in viewport should be green with a green cube over the sphere.