Currently if you add a field in the fields parameter with a wildcard, no fields will be added to the hits layer. The situation is even worst if the wildcard matches the field name of the geo_point or geo_shape field, in that case a ClassCastException is thrown.
x-pack/plugin/vector-tile/src/main/java/org/elasticsearch/xpack/vectortile/rest/RestVectorTileAction.java
return searchRequestBuilder;
    }
    @SuppressWarnings("unchecked")
    private static VectorTile.Tile.Layer.Builder buildHitsLayer(SearchHit[] hits, VectorTileRequest request) throws IOException {
        final VectorTile.Tile.Layer.Builder hitsLayerBuilder = VectorTileUtils.createLayerBuilder(HITS_LAYER, request.getExtent());
        final List<FieldAndFormat> fields = request.getFieldAndFormats();
        final MvtLayerProps layerProps = new MvtLayerProps();
        final VectorTile.Tile.Feature.Builder featureBuilder = VectorTile.Tile.Feature.newBuilder();
        for (SearchHit searchHit : hits) {
            final DocumentField geoField = searchHit.field(request.getField());
            if (geoField == null) {
                continue;
            }
            for (Object feature : geoField) {
                featureBuilder.clear();
                featureBuilder.mergeFrom((byte[]) feature);
                VectorTileUtils.addPropertyToFeature(featureBuilder, layerProps, ID_TAG, searchHit.getId());
                VectorTileUtils.addPropertyToFeature(featureBuilder, layerProps, INDEX_TAG, searchHit.getIndex());
                if (fields != null) {
                    for (FieldAndFormat field : fields) {
                        final DocumentField documentField = searchHit.field(field.field);
                        if (documentField != null) {
                            VectorTileUtils.addPropertyToFeature(featureBuilder, layerProps, field.field, documentField.getValue());
                        }
                    }
                }
                hitsLayerBuilder.addFeatures(featureBuilder);
            }
        }
        VectorTileUtils.addPropertiesToLayer(hitsLayerBuilder, layerProps);