The server is running on Ubuntu 16.04.6 LTS
SSH connection through Terminal

Yes, I am sure it is set up correctly, because, as I said, I can get information from all standard registers and blocks and all customised blocks, but no custom registers.

curl http://127.0.0.1/api/1/CountryVc returns the complete register
curl http://127.0.0.1/api/1/SomeCustomVc returns nothing (blank....0 bytes)

And yes, I have access to SomeCustomVc if I log in