Windows 10 Mobile Insider build 10586.63 is now live for those on the Insider program and in the Fast Ring



From Windows Central:

No word just yet from Microsoft on what is new, but the update is confirmed as going out to our Lumia 950 XL. However, our Lumia 950 on AT&T is not seeing the update for whatever reason and many others are not seeing the update either. Microsoft is conspicuously quiet about this update with no announcement or information.

  Windows 10 Mobile Insider build 10586.63 is now available (for some) on Fast Ring