I have a project where I have changed the User model primary key from \"id\" to \"MemberX\" using the following command in my User.php model file:
protected $primaryKey
Maybe you should check if the driver on the laravel/config/auth.php has eloquent instead of database?
'providers' => [
'users' => [
'driver' => 'eloquent', //instead of database
'model' => App\User::class,
],
database uses DatabaseUserProvider which the find method only looks on the id column.
eloquent uses EloquentUserProvider which the find method looks at the primary key if $primaryKey is defined before looking at id.