few days ago i got so mad after getting killed in blackout because of the drift that i simply pushed down the right stick and blew my life into the controller, and i also pulled and pushed the sticks up and down in the socket.
Havent had any drift since then, my guess is that there is somekind of dust inside from production, making the sensors inside the controller go wild?
This worked for me, and i hope that is working for at least some of you.
1. push down the sticks and blow hard into the sockets
2. pull and push the sticks in/out of the sockets ( i was mad so i did it really hard, be careful

Hope it helps!
Edit: i did not have the beta firmware installed