1. Have you checked that the contacts are still opted in? During campaigns some contacts may decide that they no longer want to receive emails from you and your company, so they opt out or even complain about the emails to the ISP. This means that the permission to email them will be removed from their contact record. They might also Bounce from your campaigns, this is where the email has been rejected as the email address no longer exists or their servers have rejected your message because it has been flagged as spam
2. Have you added these steps after you started the campaign? At the moment the automated campaigns work by setting them up with all of the steps and emails before starting, once started, any new steps will no be sent to the contacts
3. Have you stopped the campaign? If you have stopped the campaign half way through, this will prevent any further steps being sent to any and all contacts in that campaign.

If you are still having issues with people not receiving your automated campaign steps, please raise a support ticket