Extra Paragraph codes inserted

We have the following in a text block on our home page (always entered on the “Text” tab of the editor):

<div class=”js-video [vimeo, widescreen]”><iframe style=”width:100%; height:100%; frameborder:0; byline:0; title:0;” src=”//player.vimeo.com/video/98497797″ webkitallowfullscreen mozallowfullscreen allowfullscreen seamless></iframe></div>

———–

After we save this code and access it again on the “Text” tab of the Edit, there is an extra “<p>” added at the beginning and a pair “<p></p>” added at the end to result in:

<p>
<div class=”js-video [vimeo, widescreen]”><iframe style=”width:100%; height:100%; frameborder:0; byline:0; title:0;” src=”//player.vimeo.com/video/98497797″ webkitallowfullscreen mozallowfullscreen allowfullscreen seamless></iframe></div>
<p></p>

Can you explain why these are added? Note: We remove all blank lines before and after the code.

Since the first “<p>” doesn’t have a matching “</p>” I’m especially concerned that we have an unmatched “<p>” or “</p>” somewhere in our code. Do you have any idea why these codes are being added? Can you help me narrow down where the source of the issue (possibly a code file or another page’s code?) is?

Thanks in advance for your help in troubleshooting this.