I have no idea what causes this, but when I try to remove vertices from groups that don’t have any influence on it and normalize it nothing happens. The entire mesh is selected, I go to weight tools, hit clean, and then nothing happens whatsoever. Doesn’t matter if I click deform pose bones, all groups, active groups, or anything. Is there some setting I need to enable first?
Check if the Vertex Groups are locked.
Really hard to see your blend. You can post one here and then post the URL. Unless of course you want constant guesses. Version of blender?
Reinstalling blender fixed it perfectly.