V.O.R.E. Station

First time actually posting here, but there's something I noticed with the "Eggnog Town" redgate map that I want to address

For some reason, one becomes unable to send messages over the radio headsets when they go to the underground section of the map (also where the hotsprings are), but they're still able to receive messages. Of course it's still possible to both send and receive messages on the surface level of the town, but what I want to know is if this was an intentional direction by the map makers? Or if and how can this kind of issue be fixed?

So this isn't the best place to ask because this forum is rarely checked, but I think it's just likely that there is not a preset comms relay on the underground z-level, one is required for every z-level.