If you are using Podio Workflows to create or edit items, Workflow Automation will not be able to trigger off these events as there are no webhooks sent from Podio. See this post in Podio's Help Forum.
If you're using other Integrations to create or update Podio Items, and this does not trigger the flow as setup in Workflow Automation on that App, then it's most likely that the other integration is set to "silent".
Silent will prevent Podio's normal webhooks from firing, and therefore not trigger Workflow Automation.
Integrations include but are not limited to:
More information about Integrations can be found in the Podio Help Center