I have a Squarespace site and my forms are not showing on repeated visits, apparently, because the javascript in HubSpot forms are not ajax compatible, according to this: https://forum.squarespace.com/topic/87058-why-doesnt-my-javascript-code-work-until-i-refresh-the-page
Forms API is overly complicated https://developers.hubspot.com/docs/methods/forms/submit_form
The solution is: Hubspot needs to update its javascript!
#endrant