<p dir="auto">"VIEW SAMPLES" shows 0 rows when it should show rows</p>
<h3 dir="auto">Expected results</h3>
<p dir="auto">it should show some samples from the table</p>
<h3 dir="auto">Actual results</h3>
<p dir="auto">it shows zero rows</p>
<h4 dir="auto">Screenshots</h4>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/487433/102028816-ccf9a680-3d60-11eb-879d-e6723ac2f7dc.png"><img width="1124" alt="Screen Shot 2020-12-13 at 4 24 42 PM" src="https://user-images.githubusercontent.com/487433/102028816-ccf9a680-3d60-11eb-879d-e6723ac2f7dc.png" style="max-width: 100%;"></a></p>
<h4 dir="auto">How to reproduce the bug</h4>
<ol dir="auto">
<li>open the example chart titled "Boys"</li>
<li>click "VIEW SAMPLES" in the south/data pane</li>
</ol>
<h3 dir="auto">Environment</h3>
<p dir="auto">latest <code class="notranslate">master</code> <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/apache/superset/commit/3e22668f8dddf91edf0f9a13a23ecc69fffeb7b6/hovercard" href="https://github.com/apache/superset/commit/3e22668f8dddf91edf0f9a13a23ecc69fffeb7b6"><tt>3e22668</tt></a></p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/67837651/101453197-cd6aeb00-38e3-11eb-919e-d818e2826eb6.gif"><img src="https://user-images.githubusercontent.com/67837651/101453197-cd6aeb00-38e3-11eb-919e-d818e2826eb6.gif" alt="ezgif-7-65388df35972" data-animated-image="" style="max-width: 100%;"></a></p>
<p dir="auto">this is not a regression introduced by any recent PRs.<br>
see gif, View Samples tab should show sample data of the underlying dataset in any data visualizations</p>