[DavidG]

Originally posted by PsychoTechFreak:
Just a guess, in case of the blue line does not show up in the first attempt, is the course going through unknown systems?

Not in my case. I just tested a little more and it seems it is not a case of it just not drawing the line through the one warp point. It does for a short range course. But for a longer one it sometimes does sometimes doesn't depending on the destination sector. After a bit of clicking it seems there are two roughly equal paths to the destination sector so maybe that is what is confusing it.