I am currently helping to set up a Portal instance v10.3 behind a corporate firewall. The data has been loaded as Items from the Web specifically as ArcGIS Server web services. When in Portal I have no trouble interacting with the data, saving maps, and using the internal WAB with the saved maps.
However, I am running some tests using WAB for Developers installed on my local machine v1.3. When I add a map which is shared to Everyone from the Portal instance in a new app the basemap and the extents load but none of the data loads. The Legend and Layer List are both empty.
I have also run some tests with external data loaded in the same manner specifically using the Arizona School data made available by Robert Scheitlin and detailed in the document shared in https://community.esri.com/docs/DOC-1731#comment-14022 . I have had absolutely no issues with the example and the data works without any issue in WAB for Developers on my local machine and when run off the server.
The data is stored using an ArcSDE server v10.1 and works with no issues in the Portal environment as I mentioned above. The data is also used in our existing Flex environment and is visible to all staff on the corporate network. I've exhausted all of the documentation trying to determine the issue.
Has anyone heard of a similar situation or might be aware of a potential cause?