A little more info:
I just made and saved a new map in the viewer. After referencing it via webmap id:
the JSON returned in .NET:
{"baseMap":{"baseMapLayers":[{"id":"layer0","layerType":"ArcGISTiledMapServiceLayer","opacity":1,"title":"World Dark Gray Canvas Base","url":"https://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Base/MapServer","visibility":true},{"id":"World_Dark_Gray_Reference_8618","isReference":true,"layerType":"ArcGISTiledMapServiceLayer","maxScale":70.531073500000005,"minScale":591657527.591555,"opacity":1,"title":"World Dark Gray Reference","url":"https://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Reference/MapServer","visibility":true}],"title":"Dark Gray Canvas"},"referenceScale":0,"spatialReference":{"wkid":102100,"latestWkid":3857},"version":"2.9","authoringApp":"RuntimeSDK","authoringAppVersion":"100.6.0.2513"}
the JSON returned by referencing the URL via browser: (like https://<server>/rest/content/items/<webmapid>/data
{"operationalLayers":[],"baseMap":{"baseMapLayers":[{"id":"layer0","layerType":"ArcGISTiledMapServiceLayer","url":"https://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Base/MapServer","visibility":true,"opacity":1,"title":"World Dark Gray Canvas Base"},{"id":"World_Dark_Gray_Reference_8618","layerType":"ArcGISTiledMapServiceLayer","url":"https://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Reference/MapServer","visibility":true,"opacity":1,"title":"World Dark Gray Reference","minScale":5.91657527591555E8,"maxScale":70.5310735,"isReference":true}],"title":"Dark Gray Canvas"},"spatialReference":{"wkid":102100,"latestWkid":3857},"authoringApp":"WebMapViewer","authoringAppVersion":"10.6.1","version":"2.11","referenceScale":0}
- They are the same; however, AuthoringApp, RuntimeSDK, and authoringAppVersion is different. It matches my .NET environment locally, but why is it returning that from the server? I made it with the server web viewer, not .NET
I then updated the basemap to imagery and resaved it in the viewer. After referencing it via webmap id:
the JSON returned in .NET:
{"baseMap":{"baseMapLayers":[{"id":"layer0","layerType":"ArcGISTiledMapServiceLayer","opacity":1,"title":"World Dark Gray Canvas Base","url":"https://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Base/MapServer","visibility":true},{"id":"World_Dark_Gray_Reference_8618","isReference":true,"layerType":"ArcGISTiledMapServiceLayer","maxScale":70.531073500000005,"minScale":591657527.591555,"opacity":1,"title":"World Dark Gray Reference","url":"https://services.arcgisonline.com/arcgis/rest/services/Canvas/World_Dark_Gray_Reference/MapServer","visibility":true}],"title":"Dark Gray Canvas"},"referenceScale":0,"spatialReference":{"wkid":102100,"latestWkid":3857},"version":"2.9","authoringApp":"RuntimeSDK","authoringAppVersion":"100.6.0.2513"}
the JSON returned by referencing the URL via browser: (like https://<server>/rest/content/items/<webmapid>/data
{"operationalLayers":[],"baseMap":{"baseMapLayers":[{"id":"World_Imagery_2017","layerType":"ArcGISTiledMapServiceLayer","url":"https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer","visibility":true,"opacity":1,"title":"World Imagery"}],"title":"Imagery"},"spatialReference":{"wkid":102100,"latestWkid":3857},"authoringApp":"WebMapViewer","authoringAppVersion":"10.6.1","version":"2.11","referenceScale":0}
- They are different. Note how the .NET returned identically to the one above before the change, keeping with the dark grey basemap, which is incorrect. The browser reference updated with the imagery basemap, as it should have.
Again, thank you, just a little more info, sorry for the length.