Sounds like a bug in the InfoPath Designer.
Go to Publish->Export Source Files. Create a new folder and select it.
Now, go to the folder, and open view1.xsl in notepad and search for uniqueItems. You'll have to figure out if that parameter is valid. You may want to just delete the area. Be careful - editing the XSL manually is a sharp knife and people cut themselves. Save your view1.xsl (you'll need to make sure the form isn't also open in the designer) and now right click the manifest and choose design. Test preview . If it works, save this as a new xsn.