Error when trying to change style of Excel

I need to get the labels bolded in Excel and I found this code in the FAQ:

//add this to your functions.php
add_filter('gfexcel_value_object', function (BaseValue $value, $field, $is_label) {
    // Need to know if this field is a label?
    if (!$is_label) {
        return $value;
    }

    $value->setColor('#ffffff'); //font color, needs a six character color hexcode. #fff won't cut it here.
    $value->setBold(true); // Bold text
    $value->setItalic(true); // Italic text (to be combined with bold)
    $value->setBackgroundColor('#0085BA'); // background color

    // $field is the GF_Field object, so you can use that too for some checks.
    return $value;
}, 10, 3);

After adding that and trying to download the Excel I get this error:

Error message: Uncaught TypeError: Argument 1 passed to {closure}() must be an instance of BaseValue, instance of GFExcel\Values\StringValue given, called in /var/www/vhosts/mysite/httpdocs/wp-includes/class-wp-hook.php on line 289 and defined in /var/www/vhosts/mysite/httpdocs/wp-content/themes/mytheme/functions.php:8
Stack trace:
#0 /var/www/vhosts/mysite/httpdocs/wp-includes/class-wp-hook.php(289): {closure}()
#1 /var/www/vhosts/mysite/httpdocs/wp-includes/plugin.php(206): WP_Hook->apply_filters()
#2 /var/www/vhosts/mysite/httpdocs/wp-content/plugins/gravityforms/gravityforms.php(6069): apply_filters()
#3 /var/www/vhosts/mysite/httpdocs/wp-content/plugins/gf-entries-in-excel/src/Values/BaseValue.php(175): gf_apply_filters()
#4 /var/www/vhosts/mysite/httpdocs/wp-content/plugins/gf-entries-in-excel/src/Field/AbstractField.php(76): GFExcel\Values\BaseValue::getValueObject()
#5 [internal function]: 

I also tried with having only the bold setting there but same error appeared.

WordPress version 5.5.3
PHP version 7.4.13
GF Entries in Excel version 1.8.7
Gravity Forms version 2.4.21.5