Laravel validation "exists" fails on space

I am validating input by name using Laravel 5.6. I am using the exists rule to determine that the name matches the input and that basic is equal to 1, like below:

public function rules()
{
    $this->sanitizeSpecials($this->all());

    return [
        'special1' => ['string', 'nullable', 'exists:specials,name,basic,1'],
    ];
}

Before this validates, I run the name through a sanitizer that transforms it to the case format the name is stored as in the database.

public function sanitizeSpecials($input)
{
    if ($input['special1']) {
        $input['special1'] = ucwords(str_replace("_", " ", $input['special1']));
    }

    $this->replace($input);
}

The sanitation function is correct (ex: top_fade becomes Top Fade) and specials with no spaces in the name validate correctly, but whenever there is a special with a space in the name like the example Top Fade, validation fails even though I can verify that the input value matches the value in the database. Why would it be failing like this?

via Chebli Mohamed