Login-Screen: NO password-textfield + NO user-backgrounds

dear all,
i have 2 user accounts: one administrator and one standard user.
in the lightdm - settings (that are part of the MATE-desktop settings) i have set the
GTK-theme to Matcha-azul and the
symbol-theme to Papirus
i also set the draw user backgrounds switch to ON.

Problem 1, with every fresh boot:
The login-screen only shows the names of the administrator and the standard user.

  • It does NOT show the white textfield with the blinking cursor, where the password has to be typed.
  • Even while typing the password, the white textfield does NOT show up, so it is like blind typing.
  • Only when pressing the up and down arrows on the keyboard makes the white password-textfield appear.
  • This also happens several times after logging out for switching to the other user account.

Problem 2: my user-backgrounds are NOT being shown.

  • i had copied 3 of my pictures to the “user/share/backgrounds/” directory.
  • i use 2 of them as user-background: one for the administrator and one for standard user.
  • in the lightdm - settings i can set each of them as “background”: ok, this works and shows one picture permanently as login-background.
  • But lightdm does NOT draw the user-backgrounds. even when pressing the up and down arrows for choosing a user.

i already tried to change permissions (of which i read somewhere) but without success:

sudo chmod 644 pic.jpg 
sudo chmod g+rx pic.jpg

i would be grateful if anyone could help?