I generated the rig of a model with Auto Rig Pro which works great. For the jaw, as my model is basic, I need only one vertex group for the jaw bone. I tried to use the "Clean vertex group" function in weight paint mode, but is is greyed out.
Here is an image of an attempt with a (very) basic example. The function is greyed out still. What's wrong ?
If you also have a suggestion about the way I can affect the jaw deformation to a single bone, I am interested ...