Several users are added to a series, but not added to another series I thought they would have been. Is it just possible that a user can’t be added to multiple series at once?

Hi @Rylee Morris!Users can enter into multiple Series at the same time. Have you double-checkedthat they actually match the entry rules for that second Series? Note, if there is an Event Trigger to enter the Series then a User won’t enter until they Trigger that Event. You can read up on Event Triggers here.