I have a published Tile Service locally on our server, the Tile Service displays fine when viewed through the "Web Map" in portal. The service is made available as a Basemap to be accessed via the Web App Builder. Upon constructing the App the Tile Service is there as a Basemap Option. However when selected it does not display at all. Watching the network calls, no call is made to the tile service like it is when viewing that basemap through the web map.
Anyone have any solutions or ideas as to what could be causing it?
ArcGIS Server and WebApp Builder 10.4.1
Thanks Chen! We did find out that was the problem ourselves but will mark your reply as the answer.
The issue was the coordinate system was 'the same' but different (somehow).