you can try and delete the app cache on Android or reinstall the app on iOS. might be a problem with the certificate then.
also:
we recommend Hue Essentials App for Android and iOS. We are in close contact with the dev.
note: since May and in particular with this swversion the new Hue API v2 is in place. However the new API is reverse engineered at this point and implemented in the beta branch.
you can give it a try
does that work out?