TYPO3 Core

I'd like to use menu_pages or menu_subpages to show a sitemap in the frontend.
The pages have categories defined, but the page object in the frontend doesn't list them.
Only the number of defined categories is shown in {page.data.categories}, instead of an array of the defined categories.

Default template (MenuPages.html) with additional debug viewhelpers:

    <f:if condition="{menu}">
        <ul>
            <f:for each="{menu}" as="page">
                <f:debug inline="1" title="Menu object">{page}</f:debug>
                <f:debug inline="1" title="Categories">{page.data.categories}</f:debug>
                <li>
                    <a href="{page.link}"{f:if(condition: page.target, then: ' target="{page.target}"')} title="{page.title}">
                        <span>{page.title}</span>
                    </a>
                </li>
            </f:for>
        </ul>
    </f:if>