Problems with Dynamo Automation package

Hello! I’m new here… and pretty much a newbie to Dynamo.
I’m trying to use Dynamo Automation to run a script (through sandbox) in two revit projects at the same time. The script works fine when I use it in a single project. It substitutes a family for another. For example, I can substitute a window family from its name: Fixed, with Double Hung. It can do the same for any single category.

When I try to run that same script through the scenario A of Dynamo Automation… it just freezes after opening the first revit project and doesnt change anything.

Am I doing something wrong? Is there another way for doing what I want to do?
Thanks in advance.