I think there may be a subtle sequencing bug in orbital motion. Two things I've noticed on the Earth-Mars run:
[SNIP]
I'll post more if I see it again and get better info.
Ok, a little more infor that I think is related - it's a good news/bad news thing....
The good news: Mars has produced a load of export news (chemicals) that are wanted at Earth!!!
The bad news: the freighter that loaded them, "Roberts Wheelbarrow 002" seems to have gotten confused and is trying to offload them at Mars, which already has a surplus. So it keeps moving to Mars,
not offloading them (presumably because Mars is an exporter of chemicals rather than an importer), and waiting for Mars to move out from under it on a 5-day update so it can repeat the cycle. I suspect that the freighter in question hit whatever glitched my colony ship (a repeat of which I've not seen in probably a year of game time) and the freighter is now hitting the "can't offload" error and getting stuck.
This leads to two suggestions:
1) Set up an error handling routine so that when a freighter reaches a population which doesn't want its cargo, it looks for someplace else that does and heads there. If it can't find such a location, it ditches the cargo at a lost and goes back to an empty state.
2) Allow editing of destinations and/or cargo of civie lines in SM mode. Even a "clear cargo" and/or "clear destination" buttons on the shipping lines screen would probably do the trick.
John