Hi,
Thanks for reporting it.
A sub-server always shares a system Unix user and thus quotas with the parent’s domain main user. Although, this is always best to create top-level server even for sub domains.
@Jamie, however, the problem here, and which I could reproduce is that when sub-server is created and there is not enough quota left on the parent domain, it creates a sub-server but later always reports back incorrect quota (initial quota that happened to exist upon sub-server creation), even though you later increase quota for the parent server and it has enough of the space available.
Additionally, if you create a new user in a sub-server, it has an option to set quotas, which however not getting saved, and the quotas are always set as Unlimited and the user marked in red:
(you can always see the OS and the version on the URL of the screenshot)