HasOne relationship generates a loop

Describe the bug
When using the attachments with the hasOne relationship, I somehow generate a loop. As soon as I've remove the relationship the admin panel works again but I cannot retrieve the attachments anymore.

This only affects the "create" edit screen. If I edit an existing record, it works as usual.

To Reproduce
Steps to reproduce the behavior:

    public function hero()
    {
        return $this->hasOne(Attachment::class, foreignKey: 'id', localKey: 'hero')->withDefault();
    }

Expected behavior
It should be possible to use the hasOne relationship even without an existing record.

Screenshots

https://flareapp.io/share/Bm03adE5#F257

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Server (please complete the following information):

• Platfrom Version: 10.12.2
• Laravel Version: 8+
• PHP Version: 8.0