Install the After Effects CC (12.0.1) update for Mac OS X v10.9 (Mavericks):
Be sure that you are signed in and have activated the software—i.e., ensure that you are not running After Effects in free trial mode. The update will not work if you are running the application in trial mode.
This update is only available as a manual download (not through the Creative Cloud automatic update mechanism) to prevent users on versions of Mac OS X other than v10.9 (Mavericks) from installing it unnecessarily.
Adobe After Effects CS6 (11.0.3) was released a little while ago with this fix, plus fixes for many other crashes and bugs. Details: http://adobe.ly/AE_CS6_1103
> Plus in my creative cloud, my after effects says that it's properly updated.
That is not relevant to this update. This update is not part of the Creative Cloud automatic update system.
Also, read the details on the page that I linked you to, especially this part:
"Be sure that you are signed in and have activated the software—i.e., ensure that you are not running After Effects in free trial mode. The update will not work if you are running the application in trial mode. Sign in to Creative Cloud using any Adobe Creative Cloud application on your computer to activate all Adobe Creative Cloud applications on that computer.
Tip: If you’re not using a trial version, but you’re seeing the message that the update is not applicable, try one of these tips to force the application to be recognized as activated: Sign out of and then back in to Creative Cloud to refresh the activation state. Also, launching the After Effects render engine (not the full After Effects application) can refresh the activation; the render engine doesn’t have the crashing problem that the full unpatched application does. Finally, if neither of these works, uninstalling and then re-installing After Effects CC (12.0) can help."