We are 100% in ArcPro for editing the Utility Network at this point, but looking to develop further into the Utility Network with webservices. Thank you for your article on these types of topics. However, one issue that we encounter is the coordinate system/basemap incongruity.
The map's coordinate system must match the basemap's coordinate system, so if you don't have a basemap in the same projection as your data, then your data will be reprojected on the fly in the map in the web. This shouldn't cause any errors in the web, but it may affect performance.
If you follow the process for publishing services and sharing maps using the process outline in these articles there shouldn't be any problems. You appear to have taken a different process, and it's hard for me to understand what is going on to cause the issues you reported. Try following the procedures listed above, or if you feel you need to continue to do it the way you its set up now, please log an issue with technical support.