laravel 8, the accessor and the mutator not working

Question

I have a table leads, and a model Lead, inside the model I have a getter and setter for a certain attribute, however, it's not working.
using dd(1); inside shows that the function is never called.

why?

Model:

class Lead extends Model
{
    use HasFactory;

    //  The name of the field in the database is `lead_image_alt`.

    public function getLeadImageAltAttribute($value)
    {
        // dd(1); // never executed
        return "Some text";
    }
    public function setLeadImageAltAttribute($value)
    {
        // dd(1); // never executed
        $this->attributes['lead_image_alt'] = "Some text";
    }
}

Controller:

public function edit(Lead $lead)
{
    return view('leads.edit', ['lead' => $lead]);
}