Hi @danny.beyrer1 , I misread part of your earlier statement that they are not registered, and did not realize the email display rules link was broken in the previous quoted response. Please excuse me.
Here it is https://devsupport.zoom.us/hc/en-us/articles/13343538313101-Zoom-API-email-address-display-rules:
Could any of the following be true for your participants?
As for the participant ids, I believe they were also impacted by the changes outlined here since the meeting participant events are coinciding with the Meeting API, but I am double checking this.