If I try and use the mobile app,and log in via the Google credentials option, it does not work, just spins and spins.
I log in via Google on the website version without exception and it works fine on the same device, so I don't think it is a credentials issue.
Actually I've never been able to do it, I prefer the website version but wanted to see if one functionality which works poorly via the website version (updating or setting quantity of an item already in your collection) on mobile was better there.