Printing Christmas Labels and wanted the text to be red. Typed in red, but printed in black! The same thing happened when I typed Christmas letter, it printed in black and I wanted red.
You do not say what version of LibO you are using, and which operating system, as the setting details differ. However, if your font colour is set to red and the printout is black this may be due to the printer settings. On my system using the PRINT SETTINGS or PRINT shows a PROPERTIES setting. This gives a PAPER tab (Paper Size, Orientation etc.) and a DEVICE Tab, which in turn leads to a OUTPUT MODE. This should be set to COLOR. Perhaps this is set to Black.
A second place to try is the TOOLS > OPTIONS > LIBREOFFICE WRITER > PRINT > PRINT TEXT IN BLACK. this will also overwrite your colour setting.
The LibO Manuals, Writer and Getting Started and the LibO Help give lots of information on printing. hope this helps Peter