Relevanssi has a minimum word length setting that is set to three characters. Any one- or two-letter words are not indexed unless you change this setting from the Relevanssi advanced indexing settings. Sometimes it would be helpful to ignore short words but to index one- and two-digit numbers.
You can do that with a bit of help. Adjust the minimum word length to 1 or 2 depending on your needs, add this function to your site and rebuild the index:
add_filter( 'relevanssi_remove_punctuation', function( $str) {
return implode(
' ',
array_filter(
explode( ' ', $str ),
function( $word ) {
if ( relevanssi_strlen( $word ) < 3 ) {
return is_numeric( $word );
}
return true;
}
)
);
} );This function will let short numbers through while blocking short words.