This might have been mentioned already, but light travels quite slowly through the galaxy. It would take 200 years for any data signal transmission from an exploration ship to reach Sol from the edge of inhabited space. It would take 25,000 years for that same information to reach Sol from Sag A*. I haven't heard of any Ansible technologies or subspace communication relays, but if they exist, then likely wouldn't work outside of inhabited space because of a lack of relays. However, that doesn't explain why data couldn't be transmitted from within human space, or why "undiscovered" stars have Nav beacons.
The thing that really doesn't make sense however is that if we use Nav beacons to jump close to a star in human space, then what signal are we jumping to wild space? The star itself? If that is the case, then why do we need nav beacons at all?