Physics constraint to child actor component can be set in editor but not blueprint??

I have a blueprint that has a static mesh and a child actor component and a physics constraint to lock them together. When I set up the physics constraint in editor I can set component 1 to the static mesh and component 2 to the child actor. This works and when I run the objects are indeed constrained together.

However if I try to do this in blueprint I get an error: “Child Actor Component Object Reference is not compatible with primitive component object reference.”

Is there a way to set up a physics constraint in blueprint to constrain to a child actor component? Is there a way to convert a child actor component object reference to a primitive component object reference?

Well I figured out a way to do it, by getting the static mesh component of the child actor component and constraining that. Frankly not sure why the in-editor setting it working then. But for my purposes this works since I can parent the other parts of the child actor to the static mesh.