Update: The glitch may be related with the latest versions of Find My Mac and iTunes, according to testing by The Mac Observer.
Since upgrading to OS X 10.9.3, some users are reporting that their /Users folder is now hidden. This means the folder is no longer visible when looking at the root of the hard drive in the Finder, which is inconvenient for Macs with multiple users installed.
With OS X Lion, Apple took the liberty to hide the Library folder from OS X users. However, it does not seem like hiding the /Users directory is an Apple design decision. Many users are still seeing this folder after updating and the behaviour is consistent. The most likely conclusion is that is simply a bug that slipped through to final release, despite Apple’s new beta testing program. If you are affected by this bug, you can find out how to make your /Users folder visible again after the break …
Thankfully, the fix is simple. Open a Terminal and type:
sudo chflags nohidden /Users
Verify you have typed this command exactly and hit Enter. The command prompt will then ask you to enter your Mac administrator password. Your keystrokes won’t appear in the console, but this is normal. They are still being registered. Type your password and press enter. Your /Users folder will now be visible again. Close the open Terminal window to finish your session.
As usual, Apple has been asked for comment on the matter and we’ll update if we hear anything.