The "automatic" text color maps to the GTK text color instead of mapping to white or black.
Open your gtk theme (in /usr/share/themes/<name>/gtk-2.0/gtkrc on Ubuntu) and search for ntext_color. Replace the following color with FF0000 (red) for example and you will see that Libreoffice maps the automatic color to red on all kinds (white and black) of backgrounds.
The "automatic" text color maps to the GTK text color instead of mapping to white or black.
Open your gtk theme (in /usr/share/ themes/ <name>/ gtk-2.0/ gtkrc on Ubuntu) and search for ntext_color. Replace the following color with FF0000 (red) for example and you will see that Libreoffice maps the automatic color to red on all kinds (white and black) of backgrounds.