Video previews won't render

[DJCraig]

I'm having an error message every time I try to rend a video preview. It's happening every time within all the multicam sequences in my project, but not within other sequences. I've tried moving the in point and out point all over the place to various super-short segments. I've also tried enabling and disabling GPU acceleration, deleting the preview cache, deleting all other caches, switching to different preview formats (I've tried every single option for "Preview File Format" under Sequence Settings), and, of course, restarting the computer.

I'm using Adobe Premiere Pro CC 2017 on a MacBook Pro running macOS 10.12.6.