I have done all three possible locations in the Aethon System and on third and final mission it told me there was still one site to investigate. I now go into the Aethon System or any system and there are no more story missions. It seems to have failed to register one of the locations as being investigated.
I'm playing on PS4 if thats any help, not sure what other info you might need.
I'm now stuck and unable to continue the story.