Edit: 11/24 - Version 1511 Fall Update has been returned to Media Creation Tool.
Today responding to a report here that Media Creation Tool now has a line added to the Downloads page "These downloads cannot be used to update Windows 10 PCs to the November update (Version 1511)" I inquired via MVP Communications Channel and just learned that the Fall Update v.1511 ISO has apparently been replaced with original Release Version
This may have to do with a glitch also reported here on Monday that on Clean Installs that media was reading embedded Windows 8 keys to only activate the embedded version, even on PC's that also had a Digital Entitlement to Pro version. Since the version menu was then hidden, there was no way to install Professional without a workaround that was posted later in the week by MS in the thread here: How to upgrade 1511 from Home to Pro? - Microsoft Community
Since there is no response from the Windows 10 Team yet we assume they are scrambling to resolve issues with Entitlement activation which unfortunately was the only feature not able to be tested (or Stress Tested, as August proved) by the 5 million Insider previewers, who used keys.
We are hoping they get back to us soon so we know what to advise users. Meanwhile watch for the Fall Update 1511 via Windows Update if you are waiting to Activate Upgrade with the Windows 7, 8 or 8.1 Product Key, which is an expensive feature MS added in 1511 to try to help ease the situation.