Diplomacy : If you receive damage from an NPR, the DR goes to -101. It should then goes back to zero if there is no longer figth between the two factions, but it seems to be frozen at -101 in my game for some decades now. Communication were not etablished, but if I SM Est comm, the DR will normalise slowly like it should.
Also, anyone managed to etablish communication with NPR? I've met two so far, sent a diplomatic ship but each time I received threat message when it was in their homeworld, and no communication attempt. They even started to fire on those ships... Maybe I'm unlucky