Solved my own problem 😉
When I moved over to the new domain, some pictures didn’t transfer over. The iPhone photo had a space available, so even though the photo was deleted, it was looking for it for some reason (even though it had no intention of displaying it). I found its grey box in the page builder sitting in a column. After I removed it, the padlock was back.
Just in case other people have this issue as well, just check everything on the page, even blank sections.