What does "Downloading flow code from storage at None" mean?

[nchammas]

I'm trying to debug a deployment that doesn't seem to do anything anymore. It was probably cause by a recent update we made to the Prefect agents.

The flow run logs open with:

Downloading flow code from storage at None

This seems incorrect. Our flows are deployed to S3, so that's where they should be downloaded from.

So why might this be happening? What are the first few things I should check?