This appears to be working as intended.
The rules for aborting flights are that it will always complete the current stage, and that any charged jump has to complete too.
The “departure” phase is your ship moving away from the starting planet or station to a safe distance to perform the jump. This usually takes a few hours. During that time it also charges the jump drive. So cancelling during departure will result in at least one jump occurring, since the current stage (departing) has to complete, and by the time it does the jump drive is fully charged, so also has to complete.
So your ship will end up in a random location in Antares II. From there you can either jump back to your destination, or continue on to a new (or the original) destination. Due to the random location generally being worse than a plotted location, it’s usually not a good idea to cancel a trip on the last jump.
FYI - the reason for these apparently strange rules is to reduce the likelihood of your ship ending up stranded somewhere without enough fuel, by ensuring that all fuel expended is actually used.