Filling data in custom forms on a custom page does not work

class TakePaymentPage extends Page
{
    // ...

    protected function getForms(): array
    {
        return [
            'manualPaymentForm',
            'stripePaymentForm',
        ];
    }

    public function manualPaymentForm(Form $form): Form
    {
        return $form
            ->schema([
                Section::make('Manual Payment')
                    ->columns(2)
                    ->schema([
                        TextInput::make('customer_name')
                            ->label('Customer'),
                        TextInput::make('customer_email')
                            ->label('Email'),
                        TextInput::make('reference'),
                    ]),
            ])
            ->fill([
                 'customer_name' => $this->record->customer->fullName(),
                 'customer_email' => $this->record->customer->email,
            ])
        ;
    }
}