Hi, I found the following recent ticket that seems to be addressing the issue you are talking about: start-resin-supervisor: populate NODE_EXTRA_CA_CERTS when custom CA i… · balena-os/meta-balena@4cf8239 · GitHub
I do not think such a recent OS version is available for production download, but you may try it out on our staging environment: https://dashboard.balena-staging.com/. Alternatively you may try building an image yourself (GitHub - balena-os/balena-raspberrypi: Balena support for RaspberryPI boards).
If you download an image from the staging environment it will have a config.json prepopulated, so you still need to configure balena os configure on top of that image to change it to point to your open balena server.
Please let us know whether this solves the issue for you.
Thanks,
Zahari