When I export note to Evernote, the formula seems meet something wrong

[GuoPD]

The note file I create is like this:

Title: FormulaTest-
Notebook: Models
Tags: evnd, parameter tuning
Here is the formula test
$p$
then

The formula seems OK in the atom editor and markdown previewer.

But when I export the note to Evernote.
It just look like following:

FormulaTest-
Here is the formula test

<script type="math/tex" id="MathJax-Element-141">p</script>$p$

then

<script type="math/tex" id="MathJax-Element-142">$x$</script>$$x$$

[Note ID: b596aa733ddf6390da435678aae5968f]
2017-04-22 17:43:23

The picture of formula $p$ and $x$ are both shown. I have attempted to reimport the note from Evernote as html file. But the html file seems all right in safari.

Here is the html file generated by EVND

<!DOCTYPE en-note SYSTEM "http://xml.evernote.com/pub/enml2.dtd">
<div class="ever-notedown-preview" style="background-color: #fff; box-sizing: border-box; color: black; font-family: &apos;Helvetica Neue&apos;, Helvetica, sans-serif; font-size: 16px; line-height: 1.6; min-width: 680px; padding: 20px;">
  <p style="margin: 15px 10px 15px 0;">Here is the formula test</p>
  <p style="margin: 15px 10px 15px 0;">
    <span class="math" tooltip="p">
      <span class="MathJax_SVG" id="MathJax-Element-141-Frame" role="math" style="font-size: 100%; display: inline-block;" title="MathJax_SVG">
        <img src="?hash=510177c783affdd7a672d305f141cdd3" title="svg18d8f9c76510cb1998fd5dc68dc431ec.png" style="height: 1.583ex; margin: 1px 0ex; max-width: 100%; vertical-align: -0.475ex; width: 1.266ex;" alt="p" tooltip="p" id="en-media:image/png:510177c783affdd7a672d305f141cdd3:none:none">
      </span>
      <script type="math/tex" id="MathJax-Element-141">p</script>
      <span style="display:none" title="hidden_script_mathjax" class="hidden-script-mathjax">
        <code>&lt;script type=&quot;math/tex&quot; id=&quot;MathJax-Element-141&quot;&gt;p&lt;/script&gt;</code>
        <span style="display: none;" title="raw_mathjax_script">$p$</span>
      </span>
    </span>
  </p>
  <p style="margin: 15px 10px 15px 0;">then</p>
  <span class="math" style="display:none;" tooltip="$x$">
    <span class="MathJax_SVG" id="MathJax-Element-142-Frame" role="math" style="font-size: 100%; display: inline-block;" title="MathJax_SVG">
      <img src="?hash=3510d57be68438649838f26ba8bff769" title="svgdaa23cc5e3d9d0e3e69a01d9a3a2b58a.png" style="height: 2.058ex; margin: 1px 0ex; max-width: 100%; vertical-align: -0.158ex; width: 3.641ex;" alt="$x$" tooltip="$x$" id="en-media:image/png:3510d57be68438649838f26ba8bff769:none:none">
    </span>
    <script type="math/tex" id="MathJax-Element-142">$x$</script>
    <span style="display:none" title="hidden_script_mathjax" class="hidden-script-mathjax"><code>&lt;script type=&quot;math/tex&quot; id=&quot;MathJax-Element-142&quot;&gt;$x$&lt;/script&gt;</code>
      <span style="display: none;" title="raw_mathjax_script">$$x$$</span>
    </span>
  </span>
  <div style="display: none; margin-bottom: 0;" title="evnd-note-id" id="evnd-note-id">
    <p style="margin: 15px 10px 15px 0;">[Note ID: b596aa733ddf6390da435678aae5968f]</p>
    <div style="display: none;" title="evnd-time-stamp" id="evnd-time-stamp">
      <p>2017-04-22 17:59:13</p>
    </div>
  </div>
</div>

er..It seems the tag Style="display: none;" doesn't work. How did this problem happen?