Could you paste here the selector for the “Open” button? How is it stopping the process? Do you have an error in Orchestrator?
Are you using Orchestrator CE: https://platform.uipath.com/? If not, please provide Orchestrator version.
What Studio version do you have?
Can you try with Upload window(and Open button) from Notepad?
I’m asking you all these questions because I couldn’t reproduce(Studio CE 2017.1.6522 - my workflow uploads a package in Orchestrator; starting the process from Studio & Orchestrator works fine).