I reported on this feature's complete dysfunctional status back in 3.0 Beta 1. I couldn't even see the three traders that were hand placed by FDEV for testing purposes even though I knew where all three of them were.
Of course, nothing was done, and the same messed up system made it all the way through Beta and into the release. Amazingly, it continues to exist in the identical state in 3.03.
I guess FDEV wants everyone to use INARA instead.
If only it were usable.