It's been a few months since your post. I'm sorry I haven't follewed up sooner. Have you resolved the issue? If it is still a problem, I recommend deleting the Launch page from your object, saving the object, reopening it, and recreating the Launch page. Make sure the Launch navigate stage refers to the root element in the Application Modeler and that the Launch action is selected for that element. If these things don't work, I think you should open a ticket with Blue Prism support.