I have an issue where if I use the measure tool to add some markers on the map like this:

and then start a PrintTask to print the map, then the print task fails with a timeout error. The error does not happen if I clear the measurement markers before printing.
When checking the ArcGIS Server logs for the print service I see these WARNINGS for the marker png image?
The server name or address could not be resolved (WinINet Error while using HTTPS security, 12007), URL = http://js.arcgis.com/3.15/esri/dijit/images/esriGreenPin16x26.png?v=20160118

Does anyone have any idea what could cause this? I don't use HTTPS to access the print service.
Thanks,
Yohan