Hi:
I cannot duplicate your problem. I just tried a Web Report against an information map, and all the date format choices worked in my report.
Web Report Studio only uses ODS for returning stored process results. So if your issue is with the format used in the stored process, then you might wish to talk to the stored process author. If you are building a report based on an information map and you find that your date format is not working with the data from the information map, then you might wish to talk to the information map designer.
If either of those people is unable to help you with your format question, then, your best bet for help is to contact SAS Tech Support.
cynthia