I'm aware of some problems yesterday in Public with polygon rendering, but I think those have mostly been cleared up. If you are still having issues with polygon rendering, can you let me know:
* What version of Tableau are you using?
* What is the source of the spatial data in your workbooks (e.g., shapefile, etc.)
* Can you send the link to the public workbooks?
* Can you attach a workbook that isn't working correctly in Public?