Hello and thanks ahead of time for taking a look at this with me!
I have duplicated our production space from the spaces panel, added a user to that space through Space Management/Space Membership.
The space shows up under the user in User Management. The user has also been added to a Space Group in the duplicated space.
However when the user logs in to Birst they do not see this space at all. I was hoping someone else had ran into this and may no where to go next. I tested adding another user and the behavior was the same, so I assume its some setting on the space and not the users themselves.