Just downloaded it - It took a minute or so to download upgrades after first launch, but no issues getting in.
I use Facebook sign-in.
Thanks for the reply.
I just tried again today and it downloaded another set of updates after launch and then it logged me in directly. So the issue appears to be that I had not received those additional in-app updates that are usually pushed automatically when you launch the app.
All good now.
Those updates are really slow though.