I am on the internal windows 10 preview program. The preview application can't connect to realms by design. Realms are not shown on the worlds tab. However Friends (on public release clients) are shown on the friends tab when they are connected to a Realm. when I tried to join my friend it attempted to connect and corrupted the realm. The world can no longer be accessed by preview or public clients (iOS or Windows 10). It can be played locally on iOS after downloading it. But even downloading and re-uploading didn't fix it.