You can't see beacons when logged out in the iOS app, but can when you're logged in, it simply means your beacons have a custom UUID.
On Android, our app can scan for all beacons in range, regardless of their UUID.
On iOS however, the iBeacon API requires apps to know at least the beacons' UUID before it can detect them. When you're logged out, we scan for the default UUID all Estimote Beacons ship with. If you change the UUID to a custom one (as you should for deployment), then the app can no longer detect them. However, if you log in, then our app retrieves your custom UUID from your Estimote Account, and then can detect your beacons.