attendees not being able to join

We have a few public classes we offer where the link is posted on our website.  We recently had a zoom bombing and added a waiting room to help prevent this.  The last 2 classes we held had attendees and seemed to be working fine. Then we received messages that folks could not join and they saw the message waiting for host to join but the class/zoom meeting was happening. Any advice? I do have it set that participants can join anytime.

Thanks!