Problems Exporting with Auto Tone Mapping

Apologies if there's a super obvious solution to this that I'm missing, but I could use some clear guidance.

I've got a multicam sequence that was all shot in Panasonic V-Log. I have auto tone mapping enabled, and the footage looks great. However as soon as I send the sequence to Media Encoder for export, all the footage is the default washed-out log footage look, as if there has been no LUT applied. (For clarity, not LUT has actually been applied to the footage in Premiere, just the auto tone mapping).

And as a fun little wrinkle, trying to export the sequence within Premiere just throws up extremely unhelpful error message. See attached for the screenshot.

What's the story here? How can I get ME to export the footage as it looks in Premiere? TIA.