I have seen similar posts about hosted features, some used in printing services, but none that quite match our scenario.
We use a watermark feature made available on a https://services5.arcgis.com URL and these are usable and visible when used in maps and applications in both Map Viewer within ArcGIS Online and with Web Application Builder. However, when we try to print those maps via a self-published print template service (-either using the 'Export map' REST URL as per Organization > Settings > Utility Services), or more likely via a Print widget within the web application, we see the following error (-obfuscated for security) in Server Logs:
"Error executing tool. Export Web Map : Layer "WatermarkLayer": Failed to create layer from service at https://services5.arcgis.com/XXXXXXXXXXXXX/arcgis/rest/services/WatermarkLayer/FeatureServer/0. Failed to execute (ExportWebMap). Failed to execute (Export Web Map)."
We use a proxied DNS for both the underlying map REST service and also the printing service.
We have tried in the past an "allow-*" CORS header (-for example) on the proxy, but don't believe this made any difference, and I have read too that it is possibly due to Windows Authentication / IWA settings on IIS, but we have disabled WA as part of our access policy and are unlikely to be able to rescind that.
Has anybody else seen that issue using a hosted layer, particularly via a print template, and managed to get around it ? We are particularly interested in hearing about solutions that might require firewall, proxy or routing configuration for the proxied DNS.
For reference we are using standalone ArcGIS Server 10.8.1, and seeing this in AGOL (-ie NOT Enterprise Portal). Thanks