Arcgis rest map service issue, has anyone else seen this?

I am using Cesium 1.7.1 and trying to get base layer imagery on my globe from an Arcgis server. I can load the maps fine in everything else except Cesium. In cesium, it stretched the imagery as if it were on a different type of ellipsoid. Part of Russie gets cut off on the globe. Has anyone seen an issue like this before? I am leaning towards a server side issue serving the imagery, but I cannot really prove it yet.

Code snippet:

var serverURL = "http://serverIP:6080/arcgis/rest/services/BaseMaps/maplayer/MapServer";

var provider = new Cesium.ArcGisMapServerImageryProvider({
          url: serverURL,
          ellipsoid: Cesium.Ellipsoid.WGS84,
          maximumLevel: 3


Issue that I am seeing:

I have now updated to 1.21 and still see the same issue. I have another layer that is served up in web mercator that works fine, the one shown here is in another projection.