[Brandt Horrocks]

I haven’t had issues with files like those. When I had this problem, it was a .mov file (which is a container for some other codec anyway).

This problem can also happen when after effects misplaced your footage (or you moved it and it got confused).

In the middle of a project, I reorganized some of my stock footage, the main premiere project was not showing the bars, because a preview had already been rendered, but when I did a full export, the bars showed. After replacing my footage by redirecting the correct location, it worked just fine.