Upload Custom Mime Types in WordPress (SVG, WebP)

I have a plugin I created to allow for us to add additional image types (webp, svg, etc). For some reason it is failing and will not allow me to add svg.

Could use an extra set of eyes on this one please:

function pmp_custom_upload_mimes($existing_mimes = array()) {
    $existing_mimes['webp'] = 'image/webp';
    $existing_mimes['ico'] = 'image/x-icon';
    $existing_mimes['svg'] = 'image/svg+xml';
    
    return $existing_mimes;
}
add_filter('mime_types', 'pmp_custom_upload_mimes');