Are you still experiencing this issue? This issue can happen if there is a proxy server in your environment in front of Tableau Server.
If that applies to you, try adding a proxy exception for localhost on the Tableau Server machine.
1. Use the Tableau Server Run As User account to sign in to Windows on the computer running Tableau Server, and then open Internet Explorer. For more information, see Run As User in Tableau Help.
2. In Internet Explorer, select Tools > Internet options.
3. On the Connections tab, click LAN Settings.
4. The Use a proxy server for your LAN check box should be selected. If this check box is not selected, you are not using a proxy and the issue in this article doesn't apply.
5. In the Exceptions field, add localhost, and then click OK three times.
6. Restart Tableau Server.
If you do not have a proxy in your environment, are you able to connect to the published data sources in Tableau Desktop? If so, does re-publishing make any difference?