My fleet was instructed by the advisor to go kill some space monsters in a nebula. After the first ship arrived all the others jumped out of hyperspace at the same time even before properly arriving which means they are now in the interstellar space just outside the system. When I click in the nebula to try to regroup them the fleet wants to jump to the other system first and then go back instead of just doing the short jump directly into the nebula.
Here are 2 pictures with the situation:
Also the jumping out of hyperspace before arriving is sometimes a problem even in normal systems without nebulas, and it means that the first ship that arrives is outnumbered unnecessarily because if takes up to 30 seconds for the rest of the fleet to reengage the hyperdrive and arrive.