I see similar behavior, i.e. blue screen after supplying password. I straced the whole thing. The Xorg wrapper fails, issuing the following message. AFAICT this message isn't logged anywhere.
1841 1500648896.782569 write(2, "/usr/lib/xorg/Xorg.wrap: Only co"..., 76) = 76 This is "Only console users are allowed to run the X server" and indeed putting allowed_users=anybody in /etc/X11/Xwrapper.config gets past this particular issue. However the result is then a black screen instead of a blue screen, so it's not really much forward progress! I can see in ps that there are a lot processes (marco, mate-panel, caja, etc) running so it's certainly started a session; it's just not displaying it for some reason. ttfn/rjk
