Zoom -> Hubspot integration failing

I have a HubSpot form that is meant to register people to a Zoom webinar using the meeting ID. I have three of these forms and three different webinars active. For some of the forms on HubSpot there is no errors with a specific contact registering. However for the same contact on just a different webinar I am getting this error back from HubSpot and the workflow is not completing: "Got User not found error from Zoom API".

All the zoom webinar ID’s are correct. The Zoom integration in HubSpot can see all three webinars and can sync to them. The strangest part is that the user with the same email can register for one webinar no problem but the other two return the error.