Quassel-core / quassel-web do not store networks

I have quassel-core and quassel-web containers running on 2 different machines.
I can set up and save identities in quassel-web.
They are stored by quassel-core and next tie I connect quassel-web, they are still there.

Unfortunately if I set up networks and then save them, nothing does not seem to be actually stored.
There are still no networks in the client that I can connect to.

Not sure If I am doing something wrong, but to me it looks like a buggy setup. It is surely not a bug in quassel-core, as this would have been discovered by many people already.

Any help appreciated.