First we must know if it’s actually that plugin causing the issue. So please test by disabling the plugin (or even better, all other plugins too) and then validating your story again.
The next step is that we will do some testing to see whether we can reproduce the issue, and whether it is an issue on our side or that other plugin’s side.
I would suggest you to reach out to that plugin’s support so they can check it out.
In the meantime, I recommend disabling the plugin or trying out the official AMP WordPress plugin as an alternative that is known to work correctly.