Create a new file with default font Arial size 10. Type something. Insert a new table. The default font for this table is Liberation Serif size 12. This is not the expected behavior.
Please reset user profile and retest... Default Style defaults use Liberation Serif 12pt font. Text Body defaults uses Liberation Serif 12pt font. Table Contents defaults also uses Liberation Serif 12pt font. Put another way, if you modify the Default style for use, you will also need to modify the Text Body and the Table Contents (and any other styles) to match. If you want to keep those style modification for reuse--save them as a template document and open new documents against that template.