Some proxies being created without audio

Hello, all -

I've got a project full of 4k footage that I've created 720p proxies for (Apple ProRes 422 (Proxy)).

The original files are all the same format, shot on the same camera and all have audio. The proxies were made in one batch, all with the same profile. But most of the proxy files don't have audio included. And the pattern of proxies with and without audio seems random.

I've searched the community here and found that sending a file to Audition has helped some people, but that's not helping me. The proxy files that don't have audio in Premiere don't have audio in the files themselves. It doesn't seem like a Premiere glitch so much as a Media Encoder glitch?

Anyways, any wisdom would be most appreciated.