IN Studio, you can run individual workflows separately depending on how you have designed it. However, when running in the orchestrator, it uses one xaml file as the workflow where it starts the execution from. This you can see in Studio as well. If you go to the project panel, you will see that main.xaml is set as the default main workflow and will shown in a bold format. This means, whenever the project is executed, main file is the one that will get executed first.
So, if you want other workflow files also to be executed, what you need to do is that you need to invoke them inside the main xaml file. For this, you can use invoke workflow activities in the main xaml files sequence which enables you to invoke other workflows.
Place them in the order you want the files to be executed and then publish the project to the Studio and try again…