The alias docker-arender.packages.nuxeo.com doesn't seem to work as expected whereas docker-private-arendor-group.packages.nuxeo.com does.
NCO did an attempt on 16/01/2020 around 10:40 PM, here the result:
# docker pull docker-arender.packages.nuxeo.com/arender-converter:4.0.6
Error response from daemon: manifest for docker-arender.packages.nuxeo.com/arender-converter:4.0.6 not found: manifest unknown: manifest unknown
# docker pull docker-private-arondor-group.packages.nuxeo.com/arender-converter:4.0.6
4.0.6: Pulling from arender-converter
8a532469799e: Already exists
32f4dcec3531: Already exists
534bcab8162a: Pull complete
5aa5564f3ecf: Pull complete
Status: Downloaded newer image for docker-private-arondor-group.packages.nuxeo.com/arender-converter:4.0.6
We've already experienced this kind of issue with Jenkins X, at this moment a cash refresh seems to have fix the issue.
But it seems it still there.