The details are here: https://station.railway.com/questions/unable-to-deploy-service-ef7d6343#z40k
Apparently there is some difference in the image that I pull from atcr.io and the Docker image that I get if I just add a useless RUN echo 'hi' layer to a docker image.
I'm not 100% sure this is an atcr.io issue, but there is some difference between atcr.io and the image that Docker creates it seems.
I'm not exactly sure how to debug the difference, but Railway claims that the workdir does not exist on the filesystem. While Docker doesn't have trouble it, Railway seems pickier, and they aren't using Docker, they have their own system.