If you want to use iFrames you have to have the line below in your <head> to bring in the supporting script.
<script custom-element=”amp-iframe” src=”https://cdn.ampproject.org/v0/amp-iframe-0.1.js” async></script>
For me the AMP plugin is adding it successfully but I had to include the line below in my custom template to make it happen (if you aren’t using a custom template then I think the plugin should take care of this):
<?php do_action( ‘amp_post_template_head’, $this ); ?>
If the above code is working you should also see the canonical to the non AMP page and the line below:
<script src=”https://cdn.ampproject.org/v0.js” async></script>
If you don’t see either of those then you need to work out why the action isn’t happening. If the others are there then you need to work out why it isn’t also adding the iframe code. It looks like it only adds it if it detects the requirement so maybe your iFrames aren’t valid? If all else fails you could add the line to your template manually – I’d at least try that to confirm that it’s the problem.
