ArcGIS Tiled Map Service not displaying in Georcortex Viewer

Hi, I'm currently using Geocortex Essentials Viewer 4.14, and have discovered a weird issue with ArcGIS Tiled Map Services where they don't display.

We have a series of aerial imagery services published to a standalone ArcGIS Server Site incorporated on our Geocortex Map. In an attempt to get the viewer more responses I've republished one of the services and generated a map server cache with tiles for it to use.

I can confirm that the Tiled Map Service draws correctly when viewed in any ArcGIS products - however, the map service (listed as an “ArcGIS Tiled Map Service” in Geocortex Essentials Manager) no longer draws and is grayed out in the Layers List.

Has anyone else experienced this behavior?