touch,
I have encountered the issue where when an item is created by a workflow, another workflow that should trigger on creation doesn't trigger. I would use either of the 2 options below depending on how complex your second workflow is.
Instead of using 2 workflows, just use the one 2013 workflow. When your app step creates an item in the second list send the first workflow to a new stage to execute actions on the second list (you would need a reliable value in a field in the second list to do a look up for this to work well). After you are done you can route the workflow back to it's normal flow.
Design a SharePoint 2010 workflow for the second list and publish it. Then after you create the item with the first SharePoint 2013 workflow, use the "Start List Workflow" action from within the first workflow to start the SharePoint 2010 workflow on the second list.
Hope this helps. By the way do indicate more details on the workflows to give a specific answer like is the first workflow a site or list workflow and what sort of actions are involved in the 2 workflows.