Are you able to view the dashboards from within your Public account? A key way I troubleshoot Tableau Public issues is to try and figure out if it's the visualization or the page I embedded it into. If I can see the Public visualization at the root URL - http://public.tableausoftware.com/views/<Name of the Workbook>/<Name of the Sheet/Dashboard> (example: http://public.tableausoftware.com/views/Offences_Map/Dashboard1) then that usually tells me that something about the way the view is either embedded in the page or that some other element on the embedding page is causing the issue.
Hope that helps. Let me know what you can figure out and if you have any follow-up questions.