I have an automation set up where anyone who signs up for my newsletter (from a pop up, sidebar, or bottom of post form) gets added to the same sequence. The sequence has not ended, and yet some of my subscribers are marked as completed and not receiving more emails in the sequence. There doesn't seem to by any consistent reason as to why they've completed the sequence when they should still remain in it. How come this happened? I have been adding emails to the sequence each week...not sure if I broke something in doing so?