We just started noticing an issue with one of our ArcGIS Server environments that is at 10.4.1. After stopping a map services, we are unable to start the map service again. The only way we can get it to start again is to restart ArcGIS Server. When AGS comes back, the map service is in the stopped state and we are able to start it again. Though if we repeat stopping and then starting, it never starts again. This is the case with any service, including all of the system services (caching, publishing, etc.). We have worked with customer support, thought I would check here as well.