When working in a JACE and you discover then add Edge 10s under the Niagara network, the "Type" defaults to "Niagara Edge Station" - this needs to be set to "Niagara Station"
The answer is pretty much the above, but to expand a bit; when you add an Edge 10 to a Web Supervisor Station, it needs to understand it is an Edge 10 so it consumes the correct amount of the "Device" license, i.e. 0.1 device. Therefore, the type should be set to "Niagara Edge Station".
However, when you add an Edge 10 to a JACE's Niagara network, it does not have the concept of the device license limit and does not understand this "type". Therefore as you add the Edge 10, change the type to "Niagara Station" and then proceed to add authentication details, connect and accept Edge 10 in allowed host etc. and you will be good to go.