It's most probably due to this mesa bug: https://bugs.edge.launchpad.net/ubuntu/+source/mesa/+bug/638725 Feel free to re-open if the upcoming mesa fix doesn't solve the problem.
It's most probably due to this mesa bug: https:/ /bugs.edge. launchpad. net/ubuntu/ +source/ mesa/+bug/ 638725
Feel free to re-open if the upcoming mesa fix doesn't solve the problem.