Doing some tests the past couple days, I wiped out the Maya folder and let Maya rebuild a fresh one. Looks like the Animation & Rigging Tools are working fine! Not sure what the culprit is… slowly re-adding my other scripts and plugins back.
So, in case you have some strange issues, try making a copy of your maya prefs folder (usually in My Documents\maya), and delete the folder for your current maya version, relaunch maya and tell it to not copy old preferences (if you have any other versions of maya installed).