I have the same problem with the update. My Samsung Portable T3 1TB SSD (USB 3.1) was not recognized after the update.
It was shown as RAW instead of NTFS. On my notebook which had not yet installed the AU, it was recognized properly and as NTFS. I tried removing the USB drive and uninstalling it from the device manager and removed drive letters that were assigned to it.
After rebooting and repluging, it was still detected as RAW. I also tried installing the latest USB drivers and other new drivers that i found on my motherboard vendors website but it didn't help.
After rolling back to the previous build, everything was back to normal. The drive is detected as NTFS etc...
I also once again tried upgrading to the new build but unplugged the drive and uninstalled it from the system before the upgrade, but the result was the same after plugging it back in... Same problem on other USB ports.
Strange enough, my 64GB USB 3.0 stick seems to work just fine on the same USB port and it is also formatted as NTFS.
And it seems like we are not the only ones. A quick search shows that many people are affected from this problem.
See:
https://www.reddit.com/r/Windows10/comments/4vyifo/bug_windows_10_anniversary_update_tanked/
https://www.reddit.com/r/sysadmin/comments/4vycur/windows_10_anniversary_update_deleted_a_whole/
http://www.tenforums.com/general-support/58573-windows-10-anniversary-update-problemas-not-recognizing-external-hdd.html
http://www.omgubuntu.co.uk/2016/08/windows-10-anniversary-update-delete-partition
Here a short overview of my system:
Motherboard: Asus Maximus VIII Ranger
Motherboard Chip: Intel Sunrise Point Z170, Intel Skylake-S
CPU: Intel i7 6700k
RAM: G Skill F4-3000
GPU: Nvidia GTX 980 Ti
Software: I had no security program installed at the time of the upgrade and also have no other programs that might cause a problem like this (Just basic stuff like steam, office, chrome etc.).
The only program that might have a chance of causing this could be TrueCrypt, but I don't use full disk encryption, just a virtual disk/container so i would rule it out.
@Sudeep Aprameyan: Please let me know if you need additional info about my system. It would be really great if you could help us out, as many people are affected of this and it might be a major bug with the anniversary update.