Invalid link

Thanks for reaching out. The link generated is fine. At present there are conditions whereby the AMP endpoint will appear as /amp=1, such as if you have mobile redirection applied.

Note that the different endpoints don’t make any different to AMP serving. We’re planning to default to ?amp=1 in the future for both Reader and Transitional modes: https://github.com/ampproject/amp-wp/issues/2204

Let me know if you have any further queries on this.