Weird thing just happen.
I noticed, that mission is generated on star system Dis (If I remember correct a name). But I did not accept it, just remembered that Dis system contain a derelict ship "on some distance away". Mission was withdrawn.
Few month later I was flying near that system, so jumped in and quickly loot a ship. Then I think would be nice to know if there some kind of bounties posted near before returning home, so I build a makeshift com relay and found, that "analyze derelict" mission is posted in exactly same system I currently was, so accepted. Again "on some distance away". I was scouting system for a few month with neutrino detector on, but didn't find anything. That makes me suspicious, as system even is not large. So I maximized sensor range via CC - nothing in system. Same thing in a devmode. No objects other than planets and that com relay. I suspect it could be like that:
1. Mission was generated on that derelict. But I did not know it exist, because of no com relay.
2. I scavenged a mission objective derelict. But mission remain. Yet invisible.
3. I build a com relay and accept a mission on derelict that no longer exist.
Is that possible?
I was scared to death, so loaded a last save quite distant in time, to be said. Can not reproduce a bug now. But I am not drunk enough for a hallucinating. Yet.