Private registry container

I previously set up a private registry using the v2 registry image and running it as a container.
The container starts with a volume mounted as -v /tmp/registry_store:/var/lib/registry.
(this was for play purposes).
Anyway, I added images to the private registry and under /tmp can see
And when I run
curl https://centos7:5000/v2/_catalog
I get

I then stopped and removed the registry container and reinstalled the registry again with the same volume from /tmp/registry_store, expecting that curl would give the same result as data was stored outside of the container.

But instead …
curl -k https://centos7:5000/v2/_catalog

So obviously I have misunderstood something here.
This is setup which is about 2 years old so docker has moved on since then but I am interested to know what is happening.