They are not working currently. They did work for a good while, and they are really nice when you can use them. However, VR has started a round of adjusting/balancing class abilities and they needed to have all abilities at Mastery 0 in order to get the base level of abilities correct. So they turned off Mastery.
I don't know what VR has said about if they'll be back for EA, that would be a great question to ask Joppa on one of his streams *wink*
One of the important decisions to change
Mod edit: removed link to a browser game. Please find another forum to advertise games on, this forum is for Pantheon.