Magento – terms checkbox missing in checkout

In Magento 2.1.7 when arrive to the payment checkout there is a line for the terms: I accept the terms and conditions but there is no checkbox.

When I click on pay button it displays an error message that I have to accept the terms, but I can't accept them without checkbox!

In

magento_root/vendor/magento/module-checkout-agreements/view/frontend/web/template/checkout/checkout-agreements.html 

can see the code:

<div data-role="checkout-agreements">
<div class="checkout-agreements" data-bind="visible: isVisible">
    <!-- ko foreach: agreements -->
        <!-- ko if: ($parent.isAgreementRequired($data)) -->
        <div class="checkout-agreement">
            <input type="checkbox"
                   data-bind="attr: {
                                'id': 'agreement_' + agreementId,
                                'name': 'agreement[' + agreementId + ']',
                                'value': agreementId
                                }"
                   data-validate="{required:true}" />
            <label data-bind="attr: {'for': 'agreement_' + agreementId}">
                <button type="button"
                        class="action action-show"
                        data-bind="click: function(data, event) { return $parent.showContent(data, event) }"
                        >
                    <span data-bind="html: checkboxText"></span>
                </button>
            </label>
        </div>
        <!-- /ko -->
        <!-- ko ifnot: ($parent.isAgreementRequired($data)) -->
        <div class="checkout-agreement">
            <button type="button" class="action action-show"
                    data-bind="click: function(data, event) { return $parent.showContent(data, event) }">
                <span data-bind="html: checkboxText"></span>
            </button>
        </div>
        <!-- /ko -->
    <!-- /ko -->
    <div id="checkout-agreements-modal" data-bind="afterRender: initModal" style="display: none">
        <div class="checkout-agreements-item-content" data-bind="html: modalContent"></div>
    </div>
</div>

but in the web there is:

<div data-role="checkout-agreements">
<div class="checkout-agreements" data-bind="visible: isVisible">
    <!-- ko foreach: agreements -->
        <!-- ko if: ($parent.isAgreementRequired($data)) --><!-- /ko -->
        <!-- ko ifnot: ($parent.isAgreementRequired($data)) -->
        <div class="checkout-agreement">
            <button type="button" class="action action-show" data-bind="click: function(data, event) { return $parent.showContent(data, event) }">
                <span data-bind="html: checkboxText">I accept terms and conditions</span>
            </button>
        </div>
        <!-- /ko -->
    <!-- /ko -->

</div>

So all the code that references the checkbox input is missing.

I have configured in admin panel -> stores/terms and conditions the terms with status enabled and applied automatically.

I have configured in admin panel -> stores/configuration/sales/order/payment process options the terms and conditions enabled.

As I configured the terms and conditions in both places it should display the checkbox, but there is no checkbox.

Is like the ko if: ($parent.isAgreementRequired($data)) is false always.

I cleared the cache several times: php bin/magento cache:flush

I reindexed: php bin/magento indexer:reindex

I made a setup upgrade, setup di compile and setup deploy static but still no checkbox.

Finally I tried disabling all the terms and conditions, but still can't pay. Not sure what's happening as the code of the checkout remains untouched yet.