Problems connecting spark core to smartphone

Just unpackaged two new spark cores and plugged them into the PC and neither are working with my phone (Moto G 2nd Gen running 4.4.4) the cores LED’s flash blue as they are supposed to and when I attempt to connect using the app on my phone the core changes to a breathing cyan LED as I think it should but the phone returns “could not find core” I’m running off a public network with no password. My colleagues phone (Don’t know make model or operating system but could find out if necessary) Seems to work with both devices fine.
Any help would be much appreicated.

Could you perhaps try a factory reset? Logging out/in on the app might help as well.

Thanks for the reply. I’ve tried factory resetting both to no avial. Just tried restarting the app and that didn’t work either.