A few possible things that could be causing this is possibly.
The sector is considered a hazard zone, after killing too many pirates, xsotan a sector becomes a hazard zone and won't allow npcs to traverse within for their safety, tho lengthy hazard zones do fade away after a while.
You are too close to a faction that dislikes you and won't send traders,
These two are my best two guesses as to why there may not be npcs travelling through.