HasOne relationship not updating foreignKey in parent model

protected $fillable = [
  ...
  'attachment_id',
  ...
]
public function attachment(): HasOne{
    return $this->hasOne(ProjectAttachment::class, foreignKey: 'id', localKey: 'attachment_id');
}

Section::make('Attachment')
    ->relationship('attachment')
    ->columns(2)
    ->schema([
        Select::make('type')
            ->options(ProjectAttachmentType::options())
            ->native(false)
            ->reactive()
            ->required(),
        TextInput::make('url')
            ->label('URL')
            ->url()
    ])