Yes, this is more of a bug, although I'm not posting it in the bugs thread because I'm still on v5.50, and I mainly want to know if there is some way of fixing the situation as it is. If this is the wrong forum, please move it.
Basically, for one of my factions, the mineral packets that have been sent from some civilian mining colonies only extend half-way to their target, and instead of send more out, they're now just piling up on the colonies in question. They show as contacts on the system map, and there's a huge pile of them over the sending planets, and enough to extend half-way to the main planet but they just stop there.
Suggestions? I don't really know whether they're actually delivering their minerals, but I suspect not and have stopped them sending now.