Bug in Constraint Force - returns 0 although Constraint works

Hi,
The Constraint is set up in Outliner like this:

I want to get the force with Get Constraint Force of this constraint inside the corresponding BP like this:

The output shows no force applied, which is not true as the cube (5kg) is hanging on the constraint:

And the data on Actors in picture 1 is not reflected in th BP settings, I presumed it should be the same as in Outliner (when changed in Outliner it should be automatically updated inside the BP?):

But when all 3 items (2 components and the Constraint attached to them) are inside the single BP Actor - the force is shown as expected.