Well I tried using the ant+ connections of my mobile phone. It all seemed to connect and started off okay. Even the speed seemed correct. However after just a couple of minutes I started getting power reading drop outs. It would just drop to 0w on the app and stay at 0w for about 5 to 10 seconds even though i was still pedalling and could feel the watts remain pretty constant. Not a great experience.
I ended up having to download the zwo file and riding it on zwift again.