I just purchased a Core and had it setup within 2 minutes of pulling it out of the box using the iPhone app. Very cool 
Anyway, day two with the device and the Core cannot be found with the iPhone app. I see the error “no cores found.” The Core itself is “breathing cyan” so it should be connected to wifi correctly. I reset the Core back to factory settings and was able to connect to the device with a DIFFERENT iPhone. Again, I restored the device and attempted to connect to it using the iPhone I originally setup the device with, but nothing. It breathes cyan but still says no cores found. Any help would be greatly appreciated.
Is the core listed under the devices you own already?