I’m typing this from my computer right now, but I often like to use my iPad for the internet instead. When I sign in from my iPad, it just loads the page with me signed out. I press sign in on the top right again and the page reloads, and every time I press sign in, that happens. I refresh the tab and still nothing. The password and e-mail are right, it works on Xbox.com just fine. But is this just something with Waypoint, or my device, or can it be fixed? I was also capable of signing in from my iPad in the past though, don’t know why I can’t now.
If you haven’t already, try clearing the cache and cookies and see if that helps - there’s a decent guide here on how to do it. You’ll need to log back in to any other sites you’ve logged into, so make sure to have a not of your passwords 
Out of interest, what generation of iPad do you have and do you know which version of iOS it is running?