M1(left click) is walking or basic attack, I was generally clicking in the visible/dark area, even more bottom right to where you marked.
regarding skill menu design, perhaps have a "return" button from a specific job tree to the main skill menu and some arrows leading between skills to indicate skill requirement.
and regarding my content suggestions, I know it takes time, this isn't to rush you, just to say I think currently the game would benefit more from content than from work on graphics.