Missing discard/save buttons in result in results editor

1. create a view layout like this one:

   <!--
   `nuxeo-subjectpdffolder-view-layout`
   @group Nuxeo UI
   @element nuxeo-subjectpdffolder-view-layout
   -->
   <dom-module id="nuxeo-subjectpdffolder-view-layout">
     <template>
       <style include="nuxeo-styles">
         :host {
           display: block;
         }      *[role=widget] {
           padding: 5px;
         }      .results {
           @apply --layout-vertical;
           @apply --layout-flex;
           min-height: var(--nuxeo-document-content-min-height, calc(100vh - 216px - var(--nuxeo-app-top)));
           margin-bottom: var(--nuxeo-document-content-margin-bottom, 0);
         }      .results.dragging{
           border: 2px dashed var(--nuxeo-primary-color);
         }      .ellipsis {
           text-overflow: ellipsis;
           overflow: hidden;
           white-space: nowrap;
           display: block;
           width: calc(100% - 38px);
         }      .capitalize {
           text-transform: capitalize;
         }      .decalage {
           margin-left: 15px;
         }      nuxeo-tag {
           margin-right: 2px;
         }      nuxeo-justified-grid {
           height: calc(100vh - 10em);
         }    </style>
       <nuxeo-card>
         <h3 class="decalage">SUJETS :</h3>
         <nuxeo-page-provider id="nxProvider" provider="advanced_document_content" page-size="40" aggregations="" enrichers="thumbnail, permissions" params="[[params]]" schemas="dublincore,common,uid,file" headers="{ &quot;X-NXfetch.document&quot;: &quot;properties&quot;, &quot;X-NXtranslate.directoryEntry&quot;: &quot;label&quot; }" fetch-aggregates="">
         </nuxeo-page-provider>      <nuxeo-results id="results" display-mode="table" name="[[document.properties.uid:uid]]" nx-provider="[[nxProvider]]" selected-items="{{selectedItems}}" document="[[document]]" display-quick-filters="" display-sort="[[_canSort(document, sortOptions)]]" sort-options="[[sortOptions]]" role="widget" router="">        <nuxeo-data-table role="widget" multi-selection="true" settings-enabled="true" selection-enabled="true" class="results" on-row-clicked="_navigate" draggable$="[[_hasWritePermission(document)]]" drop-target-filter="[[_dropTargetFilter]]" empty-label="Aucun résultat" icon="nuxeo:view-list" name="table">          <nuxeo-data-table-column name="[[i18n('documentContentView.datatable.header.title')]]" field="dc:title" sort-by="[[_displaySort(document, 'dc:title')]]" filter-by="title" flex="100">
               <template>
                 <nuxeo-document-thumbnail document=""></nuxeo-document-thumbnail>
                 <a class="title ellipsis" href$="[[urlFor('browse', item.path)]]" on-tap="_navigate">[[item.title]]</a>
               </template>
             </nuxeo-data-table-column>          <nuxeo-data-table-column name="[[i18n('documentContentView.datatable.header.type')]]" field="type" sort-by="type">
               <template>
                 <nuxeo-tag>
                   [[item.type]]
                 </nuxeo-tag>
               </template>
             </nuxeo-data-table-column>          <nuxeo-data-table-column name="Date de dernière modification" field="dc:modified" sort-by="dc:modified">
               <template>
                 [[formatDate(item.properties.dc:modified)]]
               </template>
             </nuxeo-data-table-column>          <nuxeo-data-table-column name="[[i18n('documentContentView.datatable.header.created')]]" field="dc:created" sort-by="[[_displaySort(document, 'dc:created')]]" flex="50" hidden="true">
               <template>
                 <nuxeo-date datetime="[[item.properties.dc:created]]"></nuxeo-date>
               </template>
             </nuxeo-data-table-column>
           </nuxeo-data-table>
         </nuxeo-results>
       </nuxeo-card>
     </template>
     <script>
     Polymer({
       is: 'nuxeo-subjectpdffolder-view-layout',
       behaviors: [Nuxeo.DocumentContentBehavior],
       properties: {      /**
            * @doctype SubjectPDFFolder
            */
         document: {
           type: Object,
         },    }
     });
     </script>
   </dom-module>
    

2. then click switch to view / Edit (in table) / switch to table editor
3. observe the Discard and Save buttons at the top-right part of the page are missing. (see missingDiscardSaveButtons.png)

Expected behavior: those buttons should be visible