Zoom invitations missing + sent again after the webinar

Yesterday we hosted webinar. There were problems with receiving link to join, especially for people who we manually approved the day (they didn't receive it). What could be wrong? Notifications were set for one day and one hour before the webinar.

Later that day, two hours after we finished our webinar, Zoom send another invitation for that webinar to everyone - why would it send it again after its done?

Thank you.