This is really driving me crazy. I'm running Unity 2019.2.0f1 on Manjaro Linux, and I cannot set the avatar mask in any animator layer. I open the animator window, click the gear icon on the layer box and the popup opens. I click the little circle next to the mask slot, and the window pops up to let me choose the mask, but it closes immediately every time, way too fast for me to pick anything. And I'm definitely not double clicking or anything. Also I can't drag and drop the mask in the slot because as soon as I click on the mask in the project window, the layer settings pop up (from the gear icon) also closes. It would be great if these options were in the layer box instead of a separate pop up window, since the box has nothing but the layer name anyway. It's just empty. Does anyone know any workaround for this? Do I have to just set the mask in a script? I would report a bug, but I don't know how to reproduce this. It wasn't happening before.