OK I have an update. I somehow managed to get onto the live chat and asked someone about this.
It seems it doesn't actually matter whether or not the Mobile Pass shows up in the mobile app - you can still stream Sports from your phone.
One of the mistakes I made was thinking I had access to all sports channels (you'd think so with a 'Sky Sports Pass') - but no, you can only access 5 Sports channels:
Sky Sports Premier League,
Sky Sports Action,
Sky Sports Arena,
Sky Sports Racing
and Sky Sports News
I had been clicking on the Sky Sports Main Event channel (which was also showing the Premier League game the other day) so it just wouldn't work. Turns out that's the reason.
Also, you cannot play on a tablet - it actually has to be a mobile phone - so when I tried on my tablet and had the same message I also got confused by that.
Hope this clears things up because it sure wasn't clear to me at the time.
