Any other ideas? Fiddler capture shows the app access my ArcGIS online account, but it keeps going back to the error message.
Appbuilder log entry: [2014-09-18 11:21:39.202] [INFO] server - No portal URL is set, redirect /webappbuilder to /webappbuilder?action=setportalurl
I filed a bug report, but haven't heard anything yet. I miss the Viewer for Flex