Another option for troubleshooting is to set the Variable named trace to "true" in your request Workflow. This will cause a lot of information to be printed to Tomcat’s standard output, which should show up in catalina.out.
You could also try searching the sources of your Workflow for the text “Your request was submitted”. If it is an out of the box message, you can check the OOTB messages list in identityiq.jar to find the message key, then search for that in your Workflows. The point of all this searching is to find where the message is coming from, then work backwards to infer where the failure is coming from.