The behavior can manifest itself in multiple areas within the ArcFM Mobile Portal including, but not limited to, Operation Layers, Creating Replicas, and Task Management. Further, the behavior can also express itself with the text: HTTP 404 error; failed to download layers.
The cause is due to a mixed secure content environment when layers from ArcGIS Server are provided through HTTP. This can either be http://servername:6080/arcgis/rest/services/ or through Web Adaptor as http://servername/webadaptorname/rest/services. Since ArcFM Mobile Portal requires HTTPS, the browser (IE, Chrome) will detect a mixed security environment and allow only secure content.
In IE, make sure you show all content once the prompt is given:
In Chrome and Firefox, make sure to load unsafe scripts by selecting the silver shield: