As of downloading the new Dashboard experience update I had a great amount of trouble using my console.
No games were working, it said I was signed in though everything else said otherwise. The top left of the dashboard (where your profile pick is) has some messed up text. Basically instead of 'Sign in/Manage accounts, it has most of the letters as either symbols similar to the original or with for example: ğ/ā or even ones I've never seen before.
Basically it leads me to believe there's a pretty huge glitch on that side of things.
I've managed to figure out a work around until the code guys get to fixing.
Step 1: Go to Settings > All Settings > Account > Remove Account. Delete your account from the Xbox One.
Step 2: Turn off your Xbox. Hard turn off pretty much. All the way.
Step 3: Turn your Xbox back on and redownload your profile.
As much as a pain as this is you will have to do it every time you turn on your xbox unless you want to delete your profile every time before you turn it off. It works for me and hopefully it'll help people to get using their xbox until the issue is fixed.
Can't moan too much about it, we all knew what we signed up for ;) hope this helps!