I would start by reviewing the docs on Creating Workflow Actions. You should also ensure that the permissions are proper for the particular action you're not seeing. If it's owned by another user and private, you'll need to make it at least readable for the role you're logged in as.
Also ensure that the eventtype and fields you've tied the action to (if applicable) are present in the event list when you try to access the action.
I am having the same issue. Permissions are global read which is fine. The workflow is not private. It will work just fine using Splunk search and reporting, however when I place a raw event table in the dashboard and attempt to activate the work flow via the Event Actions button, the workflow option is not there.