When editing particularly large workflows (eg. 15 steps, over 40 transitions), JIRA may hit MySQL's 64k limit on the size of TEXT fields. When this happens, MySQL silently truncates the data from the last edit. Trying to edit the workflow will result in an error, and the workflow will not properly display in the 'View Workflows' page. An error like the following will appear in the logs:

2005-01-12 13:07:14,979 ERROR [atlassian.jira.workflow.OSWorkflowManager] Could not get workflow called: New Development Life Cycle workflow: com.opensymphony.workflow.FactoryException: Error in workflow descriptor: New Development Life Cycle workflow: root cause: XML document structures must start and end within the same entity. (line:1280 col:24)
com.opensymphony.workflow.FactoryException: Error in workflow descriptor: New Development Life Cycle workflow: root cause: XML document structures must start and end within the same entity. (line:1280 col:24)
at com.atlassian.jira.workflow.JiraWorkflowFactory.loadJiraWorkflow(JiraWorkflowFactory.java:186)
at com.atlassian.jira.workflow.JiraWorkflowFactory.getWorkflow(JiraWorkflowFactory.java:88)
at com.opensymphony.workflow.config.DefaultConfiguration.getWorkflow(DefaultConfiguration.java:76)
at com.atlassian.jira.workflow.OSWorkflowManager.getWorkflow(OSWorkflowManager.java:152)