Office 365’s single sign-on capabilities with ADFS are a great improvement over dual-identities, and it takes online users a step closer to the seamless experience they have become accustomed to with an on premise web application. If you’re looking to set it up, Microsoft provide some great information and even some step-by-step videos: https://support.microsoft.com/en-us/kb/3061192
But, once you’ve got it all hooked up you quickly find a couple of unexpected “features” that can ruin your user experience.
If you are aware of these features and have tried everything, jump to the end of this post to see the magic! It’s not rocket science, but the workaround isn’t obvious and the technique isn’t overly well documented or communicated.