Smart campaigns: this doesn't work
The subscription doesn't show up in the subscription list.
Smart lists: this works
The subscription shows up in the subscription list
When I tried to make the smart list subscription via the smart list, I used the same name as when I tried through a smart campaign. It gave an error because I couldn't use the same name. So it seems it was somehow created but not showing?
Is this bug or am I missing something?
AFAIK, you can only subscribe to "explicit" smart lists, the ones that have an icon in the Marketo UI left column.
You probably hit a bug that allowed to create the subscription on the "member of smart campaign" though. You may want to log a ticket to support.