Single selection updates automatically, multiple selection doesn't


Working with simple model lines in Revit. I drew four connected model lines. In Dynamo, if I use SelectModelElement and show it’s length, when I change the line in Revit, the length reported in Dynamo updates to show the change. I then used SelectModelElements and selected all four model lines. The result shows length for each line, but if I change the length of any of the lines, they don’t update. If I close the Dynamo file and reopen it, the new values are shown. Does anyone know if that is expected behavior?