CKEditor changes asynchronous adsense code

Hello. I'm using CKEditor for Wordpress 4.0 and Wordpress 3.8 running Sandbox 1.6.2

Problem: When I paste asynchronous adsense code in the CKEditor's 'source' mode, it appears fine and works fine when the page is viewed. However, when I save the page, or switch from 'visual' and then go back to 'html', the code gets shortened (and consequently no ad is displayed when the page is viewed).

The problem goes away if I disable CKEditor for wordpress. Note that I also have WPAutop plugin installed.

======== Async Adsense code from google (I removed my Adsense ID):

<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- Under_Header_Ldrboard -->
<ins class="adsbygoogle"
     style="display:inline-block;width:728px;height:90px"
     data-ad-client="XXXXXX"
     data-ad-slot="XXXXX"></ins>
<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>

============== Screwed up code after saving:

<script async src="http://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script><!-- Under_Header_Ldrboard --><script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>
</p>

=======

As you can see, the code in the <ins></ins> tag is removed.

I have tried reformatting the code so there are no spaces, and changing the double-quotes to single quotes, to no avail. I've also tried changing "//pagead2" to "http://pagead2" but it didn't help. 

Lastly, the synchronous adsense code works fine with CKEditor. It's just the Async code that doesn't.

After Googling around, I found someone who suggested turning off the "Advance Content Filter" in CKEditor for a similar problem. I have not tried this yet, as it's not a simple option in the plugin's config, but requires me to edit a value in the plugin's config somewhere. Is this what is required to get Adsense code to work with CKEditor?

Any insight would be appreciated. 

MB / www.englishcurrent.com