In order to use the Browse UI, you need repository-admin read privileges (like below example). This is contradictory to search which you just need repository-view-* privileges (you need these for Browse UI as well).
I am pretty confident this is a bug, because anonymous by default cannot use Browse UI (because of this). By default, anonymous shows it has no permission to see any repositories in Browse UI.
Bringing up at least for triage; in case not a bug, don't think intuitive so I think worth documenting.
Browse UI is new to Edgy so does not affect older NX3. I did not check NX2 at this time.