Understrap theme translation directory issue

I have my language translation fa_IR.mo and fa_IR.po and understrap.pot files in theme languages directory. but theme does’nt use them.instead it uses translation in directory:

also there is load_theme_textdomain( 'understrap', get_template_directory() . '/languages' ); in theme setup, so i expected it to load translation mo file from theme languages directory,but its not.