API authorisation not working for some reason

The authorisation workflow requires a call to OAuth when there is no valid token available.

For my application, this has always looked like:

https://www.geni.com/platform/oauth/authorize?client_id=<client_...

for my dev environment dev.ancestors.net.au

This previously returned a response that looked like:

http://localhost:3000/profile_tree_geni_auth_response?code=<code...

eg back to the redirect_uri supplied

For the last 2 days this has no longer worked and instead the authorisation workflow is redirecting to:

https://www.geni.com/home

Can anyone please explain what is going on?

Thanks

Craig