Sync error when trying to update a one-to-many relationship

[Baspa]

• Laravel Version: 7.0
• Nova Version: 3.22
• PHP Version: 7.1.3

Description:

I have a Client model that can be related to many Team models:

    public function teams()
    {
        return $this->hasMany(Team::class);
    }

The Team model can only be related to one Client model:

    public function client()
    {
        return $this->hasOne(Client::class, 'id', 'client_id');
    }

I want to be able to update this Client in Laravel Nova and add more relationships. For example: a team switches to another Client so I can select another Team in the update form and add it to the Client. I tried using both Benjacho/belongs-to-many-field-nova and dillingham/nova-attach-many packages to be able to edit this model and its relationship. However, no matter which package I use I constantly get the same error:

Call to undefined method Illuminate\Database\Eloquent\Relations\HasMany::sync()

Because I get this error every time I assume this has something to do with Laravel Nova or the way I defined my relationships in Laravel.

Detailed steps to reproduce the issue on a fresh Nova installation:

1. Create a Client and a Team model in Laravel and Nova
2. Define a one-to-many relationship between those two models
3. Try to update the Client model

[crynobone]

sync() only used for attaching relation with pivot.