Ah, I found it.
Under (the cog icon) settings menu > Directories + Subscriptions.
There is a really confusing filter for your subscriptions. (I'm confused as to why new subscriptions are not added to this with an enabled status automatically).
and you need to manually add the subscriptions that you just created because it defaults to off, which is terrible UX, because if you don't know this filter exists then you end up in a bit of a bind.