product attribute – Magento 2 dynamic rows add row not working

I’m trying to add dynamic rows in the product edit page.
I have successfully added a dynamic row UI component; the problem is the ‘Add’ button is not working after one row is inserted.

Thanks!

this is my product_form.xml

<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <fieldset name="gestione_lotti_attribute_fieldset">
        <argument name="data" xsi:type="array">
            <item name="config" xsi:type="array">
                <item name="label" xsi:type="string" translate="true">Lotti</item>
                <item name="collapsible" xsi:type="boolean">true</item>
                <item name="opened" xsi:type="boolean">true</item>
                <item name="sortOrder" xsi:type="string">2</item>
                <item name="canShow" xsi:type="boolean">true</item>
                <item name="componentType" xsi:type="string">fieldset</item>
            </item>
        </argument>
        <dynamicRows name="dynamic_rows">
            <settings>
                <addButtonLabel translate="true">Aggiungi Lotto</addButtonLabel>
                <defaultRecord>true</defaultRecord>
                <additionalClasses>
                    <class name="admin__field-wide">true</class>
                </additionalClasses>
                <componentType>dynamicRows</componentType>
            </settings>
            <container name="record" component="Magento_Ui/js/dynamic-rows/record">
                <argument name="data" xsi:type="array">
                    <item name="config" xsi:type="array">
                        <item name="deleteButtonLabel" xsi:type="string">Remove</item>
                        <item name="isTemplate" xsi:type="boolean">true</item>
                        <item name="is_collection" xsi:type="boolean">true</item>
                        <item name="componentType" xsi:type="string">container</item>
                    </item>
                </argument>
                <field name="lotto_numero" formElement="input">
                    <argument name="data" xsi:type="array">
                        <item name="config" xsi:type="array">
                            <item name="fit" xsi:type="boolean">true</item>
                        </item>
                    </argument>
                    <settings>
                        <dataType>text</dataType>
                        <label>Lotto</label>
                    </settings>
                </field>
                <field name="lotto_data_scadenza" formElement="input">
                    <argument name="data" xsi:type="array">
                        <item name="config" xsi:type="array">
                            <item name="fit" xsi:type="boolean">true</item>
                        </item>
                    </argument>
                    <settings>
                        <dataType>text</dataType>
                        <label>Data Scadenza</label>
                    </settings>
                </field>
                <field name="lotto_quantita" formElement="input">
                    <argument name="data" xsi:type="array">
                        <item name="config" xsi:type="array">
                            <item name="fit" xsi:type="boolean">true</item>
                        </item>
                    </argument>
                    <settings>
                        <dataType>text</dataType>
                        <label>Quantità</label>
                    </settings>
                </field>
                <actionDelete name="actionDelete" sortOrder="30">
                    <settings>
                        <dataType>text</dataType>
                        <label translate="true">Actions</label>
                        <componentType>actionDelete</componentType>
                    </settings>
                </actionDelete>
            </container>
        </dynamicRows>
    </fieldset>
</form>